North Ops Weather-2021

[FireCapt]

URGENT - WEATHER MESSAGE
NWS: San Francisco Bay Area 1220 PM Wed

…EXCESSIVE HEAT WATCH IN EFFECT FROM SATURDAY AFTERNOON THROUGH
SUNDAY EVENING…

• WHAT…Well above average heat with widespread highs from the
  mid 90s to low 100s. Dangerous conditions with temperatures 102
  to 110 possible for the hottest interior locations. Overnight
  lows in the upper 60s/70s with some higher elevation areas
  remaining in the 80s. Onshore flow and marine influence will
  keep coastal and bay areas in the 70s and 80s.

• WHEN…From 12 PM Saturday until 10 PM Sunday.

[anvilhead]

Flex-alert issued for the entire state starting tomorrow. It could be a shaky week. A heatwave of tectonic proportions.

The heatwave won’t be as severe at the coast… so enjoy that… unless the water recedes.

[bootstrap]

Tectonic for sure. California been shaking today!

[ECF28]

Hahhahaha Bah-dum-tcchhhh

[anvilhead]

When the ridge breaks down next week there is going to be an onshore wind event. Remember we are going from very high end temperatures back down to ‘normal or just above normal’ temperatures, so adding that strong onshore flow is extremely hazardous for fire weather.

Dry lightning watch… it is way out in lalaland but the GFS wants to cut off an upper level low and interact it with a dying tropical cyclone from the eastern pacific. Hard to forecast so far in advance… but with the ridge pushing disturbances from the Gulf of Mexico across to the Eastern Pacific and the ridge transitioning to a rex block there is a chance something cuts off. It’s similar to the early August pattern of last year… will continue to monitor.

[anvilhead]

It’s been 5 days so I am updating this…

The GFS continues to show a quasi Rex block scenario developing with a strong massive high pressure system across the 4 corners region into Canada. The monsoon trough will move over Northern Baja & Southern CA into the Pacific ocean almost like a square. There should be some pretty deep moisture in Southern CA but as disturbances move over the cold waters of the pacific ocean there is a pretty good chance some of the low level moisture mixes out. The models pick up on some disturbances that could lead to elevated convection that could be on the dry side, but it’s hard to forecast far in advance.

It is my opinion that the next week or two weeks will be extremely chaotic weather wise.

The unrelenting heat in the interior will continue, the monsoon trough should lead to thunderstorms across all areas, which could lead to pyrocumulonimbus clouds on any fires, the smoke from numerous large fires burning across the west will continue to fill the sky with increasingly more smoke… including any new starts… I think far North Ops and particularly the Pacific NW will be at risk for more rounds of dry lightning as that is where PWV’s will be the lowest & PVA highest… the compounding affects of all this is disturbing heading into August & early September which is typically the most energetic, hot, & amplified the weather gets for CA.

Would love to hear someone else chime in, with their opinion.

[imetfromhotlist]

Hi Anvil- I’ll bite. In general no disagreement with your synopsis. Since this thread is listed in the North Ops wx Ill start there. The weak troughing is keeping temps near normal with a general southwest wind flow aloft. All this to say the recent fires (Lava, Salt, and even the Sugar) have been mainly fuels driven but likely helped by the three heat events so far this summer. Of course the fuels and drought data since early spring have all portended this. I like to look for “canary in the coal mine” fires early in the season, where upon retrospect we realize they were giving us clues of the upcoming season. Id say the Bootleg (Oregon) and now the Dixie Fire are those canaries. (as well as the Beckwourth Complex but that seems to be a whole other story). My point is we are seeing active fire behavior in the absence of any really unusual weather of note. (i.e no strong winds)

In terms of the forecast. Looks like moisture should increase across the deserts and portions of South Ops (Southern Sierra) as early as this weekend. As you allude to…as that moisture rotates through North Ops and into the Pacific Northwest dry lightning will be a concern later Sunday into Monday.

On the National scale, what’s most daunting in my opinion is the sheer volume of timber fires from WA to ID and MT (not to mention BC Canada) all in the wake of that historic heat event. Hard to imagine those fires not having IMT committed into Sept. Thus the early push to PL5. Meanwhile the main ridge axis looks to set up over Wyoming/Utah/CO keeping them in play as evidenced by the emerging Morgan Creek Fire. Perhaps the one bit of good news is things look wet for AZ/NM. (recall how they had their second season last year). Will we get our usual mid-season lull soon? Not looking that way as the trough off the PacNW will bring gusty southwest wind flow to those fires in ID/MT over the coming days. At the end of the day I think the current story is the fuels and drought and not really the wx. I’ll end by attaching the 4 week EDDI chart (evaporative demand drought index) which is a proxy for the stress on fuels over the last month. No surprises, just another way to look at the data. Upshot seems to be that the pre-season forecasts are coming to fruition and aligning with a post-covid climate that includes a shortage of crews and other firefighting assets. Nationally it could be a long two months ahead and for those of us in CA several months.

[anvilhead]

This is a great and helpful graphic that shows the full extent of things rather than just precipitation deficits, thank you for sharing.

[mesocyclone]

Heads up regarding potential for significant dry lightning event in CA late this weekend. These forecasts are always quite difficult, but Nick is a fire wx forecaster for NWS SPC and knows his stuff. This was the one thing I was really hoping wouldn’t happen this summer in CA–let’s hope this falls apart in model land.

Daniel Swain (Weather_West)

[fire201]

Is this forecasted to be as widespread in areas like the Bay Area/North Bay that experienced the event last August? Or is this more towards the Sierra/higher elevations?

[mesocyclone]

It’s too early to talk details, and last summer’s event near the Bay Area was so extraordinary it presents a very high bar that I’d doubt will be replicated.

That said, this event definitely has the potential to produce dry lightning far outside of the typical zones–perhaps including valleys/coastal areas even into central/northern CA. Should be clearer in 24-36 hours…

[anvilhead]

This is what I was picking up on, although you’d want the PWV to be a little lower, but fast storm motion should limit wetting rain potential. Should be easier to forecast tonight when the high resolution NAM comes into frame.

[milehighbar]

Well said. Truth👇

@imetfromhotlist

On the National scale, what’s most daunting in my opinion is the sheer volume of timber fires from WA to ID and MT (not to mention BC Canada) all in the wake of that historic heat event.

[Twigpig]

I clicked on the Tweet link and was presented with this map. Can someone please translate the meaning? Is that potential measurable rain?image|646x500

[mesocyclone]

Unfortunately, no. “Precipitable water” is an aggregate measure of the amount of atmospheric moisture in the entire column above your head. Relatively high overall PW (but dry lower levels of the atmosphere) and elevated instability are a recipe for dry lightning. It’s still early; we’ll know more by Friday, but given the broader situation right now and state of the fuels I think this bears very close watching.

[imetfromhotlist]

It’s precipitable water vapor in the whole column. Think of it as what’s available to turn into precip or RH throughput the column perhaps. The color table isn’t intuitive. The purple colors are super moist (think heavy rain with cells). The blue is values above 1inch (total value through depth of atmosphere). Usually any values above 1 inch would preclude “dry lightning. Fast storm movement and receptive fuel beds are another element to consider. For true dry events you’d probably want values 0.50 (real dry) to 0.75. Right now I don’t think this should be compared to 2020 or 2008 events. Set up is different as well as the preceding conditions. As always any lightning can be problematic, especially at PL5 in long term drought.

[anvilhead]

NWS Bay Area (NWSBayArea)

NWS Bay Area (NWSBayArea)

[FireCapt]

NWS - SF: Thought long and hard about issuing Fire Wx Watches but will wait for round of morning conference calls with land management agencies. As a compromise the forecast will now show a slight chance of dry thunderstorms. Given we are still over 2 days out confidence is moderate at this time overall. As we get closer we will start to benefit from some of the convective allowing models. During these type of elevated convection events, we dont need to worry about surface forcing so should lightning occur it can really be anywhere. However, the marine layer has helped us here locally in driving the fuels in the valleys back to near or below seasonal dryness levels. It is the dry hills where fuels are still at record dry levels with the ongoing drought that will be of most concern. For comparison the historic August 2020 and June 2008 lightning events occurred on the heels of extreme heat waves. In addition the convection had roots over the Pacific. For whatever the reason our historically bad fire outbreaks usually emanate from storms that come in from off the Pacific (1999 Kirk Complex and reportedly the 1977 Marble Cone fires). Im sure Im forgetting something more recent but one of the last big local lightning events from desert southwest monsoon moisture was the late August 2003 event that brought us the 2003 Santa Clara Complex/Devil Fire. Historically when we`ve had lightning with a well defined marine layer (which we expect this time should the lightning develop) any new ignitions dont move nearly as rapidly. The wave of moisture and instability will move rapidly inland on Monday afternoon as we return to a more seasonable July pattern. No signal for any abnormally hot weather next week.

[Twigpig]

[LOP]

Extended the FWW For much of the North State:

URGENT - FIRE WEATHER MESSAGE
National Weather Service Sacramento CA
109 PM PDT Fri Jul 16 2021

…Thunderstorms with Little Rainfall Late Sunday through Monday…

.Monsoonal moisture moving up from the south will bring the
potential for thunderstorms with little rainfall across portions
of interior northern California late Sunday through Monday.
Thunderstorms may develop Sunday afternoon over the Sierra south
of I-80, then spread northward into portions of the Coastal Range,
southern Cascades and the northern Sierra north of I-80 overnight.
Isolated thunderstorms may also develop in the Valley. Best
thunderstorm potential will be over the mountains. Given
critically dry fuels, any lightning strikes may result in high
probability of ignition.

CAZ213>221-263-266>269-279-171300-
/O.NEW.KSTO.FW.A.0003.210718T2100Z-210720T0000Z/
Eastern Portion of Shasta/Trinity NF-
Burney Basin and Northeast Plateau in Shasta County Including
Northwest Lassen NF north of Lassen NP-
Northern Sacramento Valley to Southern Tehama County Line Below
1000 Ft-
Central Sacramento Valley in Glenn, Colusa, Yuba, Northern
Sutter, and Butte County Below 1000 Ft-
Southern Sacramento Valley in Yolo-
Sacramento Far Western Placer, southern Sutter and Solano County
Below 1000 Ft-Carquinez Strait and Delta-
Northern San Joaquin Valley in San Joaquin and Stanislaus
Counties Below 1000 ft-
Southern Motherlode From 1000 to 3000 Ft. Includes portions of
Calaveras-Tuolumne Unit-Stanislaus NF West of the Sierra Crest-
Southeast Edge Shasta-Trinity NF and Western Portions of Tehama-
Glenn Unit-
Northern Sierra Foothills from 1000 to 3000 Ft. Includes portions
of Shasta-Trinity and Butte Units-
Northern Motherlode From 1000 to 3000 Ft. Includes portions of
Nevada-Yuba-Placer-Amador and ElDorado Units-
Northern Sierra Including Lassen NP and Plumas and Lassen NF/S
West of the Sierra Crest (West of Evans Peak-Grizzly Peak-
Beckworth Peak)-
Northern Sierra Including the Tahoe and ElDorado NF/S West of the
Sierra Crest-Eastern Mendocino NF-
109 PM PDT Fri Jul 16 2021

…FIRE WEATHER WATCH IN EFFECT FROM SUNDAY AFTERNOON THROUGH
MONDAY AFTERNOON FOR DRY THUNDERSTORMS FOR FIRE WEATHER ZONES
213, 214, 215, 216, 217, 218, 219, 220, 221, 263, 266, 267, 268,
269, AND 279…

The National Weather Service in Sacramento has issued a Fire
Weather Watch, which is in effect from Sunday afternoon through
Monday afternoon.

• AFFECTED AREA…Fire weather zones 213, 214, 215, 216, 217, 218,
  219, 220, 221, 263, 266, 267, 268, 269 and 279.

• WIND…Gusty and erratic winds are possible near any
  thunderstorms.

• THUNDERSTORMS…Isolated to scattered thunderstorms may develop
  late Sunday and continue into Monday afternoon. Best chance for
  thunderstorms will be on Monday, mainly over the mountains with
  an isolated potential in the Valley.

• HIGHEST THREAT…Dixie Fire in Butte County.

• IMPACTS…Potential for fire starts with any lightning. Rapid
  spread of fire possible depending on terrain and local wind
  conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS…

A Fire Weather Watch means that critical fire weather conditions
are forecast to occur. Listen for later forecasts and possible
Red Flag Warnings.