Fire Conditions expected rest of this week and weekend for California

The fire conditions Wed Night into this morning were not as severe as expected thanks to weaker winds. This allowed firefighters to make some ground against fires through the night, however high fire danger remains and will continue for days into the future, with no rain in sight.

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Strengthening pressure gradients along the mountainous terrain of interior California and the warm, very dry air mass will promote high far danger with windy conditions near the mountains and adjacent valleys Fri Night-Sunday. (See tightly packed isobars…lines of equal pressure…on the map in CA just west of Nevada as high pressure shifts SE-ward over the Intermountain West).
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Very low dew points during the day Sat could mean relative humidity values as low as 10-20% across interior California, along with gusty winds for high fire danger.

Air quality remains terrible in the Bay Area. Folks in that region should do what they can to avoid being outside if at all possible.

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Unhealthy air quality exists across the entire Bay Area. Expect harmful air quality to be problematic into the weekend.

I’ll add any additional updates related to fires on this post today. Stay safe in these areas!

–Meteorologist Nick Humphrey

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GOES-16 Satellite Loop of California Wildfire Smoke

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The new geostationary weather satellite, GOES-16 captured this high spatio-temporal resolution loop of the smoke plume over the Bay Area of Northern California this evening before sunset. The deep smoke is embedded in the low-level north winds, while the white, high cirrus clouds are in southwesterly flow. You can right click to save or open in the new tab to see the larger version of it. It’s amazing but frightening to know what’s happening under all that smoke.

–Meteorologist Nick Humphrey

California Fire Crisis (Wed Updates)

Update at 11:15 pm PDT Wed:

The Wine Country Fires in Northern California have now destroyed over 3500 structures, making it the most destructive fire event in state history. And with 23 deaths now reported, it is quickly approaching the record for the deadliest. There are still areas burned where police have yet to search for potential victims because the primary operations are focused on evacuations and maintaining safety in the current fluid situation. Unfortunately, given that the missing persons are over 280, even with many being found safe, the death toll is still likely to go up as some are found.

Amazing the disturbing level of destruction of this fire event. I was only 7 yrs old in 1991, but I remember the Oakland Hills Firestorm, as it was plastered all over the news as much as this event. I didn’t think I could imagine such a disastrous fire worse than that.

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Update at 5:30 pm PDT Wed: Update on the Meteorological Conditions in the Bay Area/Napa Valley Region.

Numerous fires continue to largely out of control over the Napa Valley/North Bay region. Heavy Smoke (with particulate matter >2.5 micrometers) is spreading southward over the Greater Bay Area reducing visibility and causing air quality to be considered very unhealthy for all individuals in the region with VERY UNHEALTHY conditions in the hilly terrain east of Santa Rosa and Oakland. If you can stay indoors, do so, especially for the young, elderly, and those with chronic breathing problems.

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Particulate smoke (<2.5 micrometers) being produced by the fires and spread southward from northerly winds. This is causing very poor air quality across the state of CA. (earth.nullschool.net)

A RED FLAG WARNING REMAINS IN EFFECT FOR MUCH OF N. AND C. CALIFORNIA FROM NOW UNTIL TOMORROW AFTERNOON. As high pressure builds across Oregon into NE. Nevada, easterly downsloping winds will intensify the foothills across the interior of Northern CA, increasing the threat for any fires which develop to spread quickly and existing fires to expand acreage quickly. These winds will help maintain very conditions longer into the night, slowing humidity recovery and allowing fires to potentially exhibit extreme behavior (heat, forward speed, self-maintenance). Winds may gust up to 45-50 mph in some areas.

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High-Resolution Rapid Refresh (HRRR) Model forecast for around 10 pm PDT showing the intensifying pressure gradient and pressure ridging over the hills and mountains of northern CA. This will lead to development and intensification of dry Diablo winds overnight.
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The HRRR forecast valid for 1 am PDT showing widespread dew point temperatures in the mid-20s. With temps in the mid/upper-50s, this means humidity values in the 25-35% range, keeping fuels relatively dry for spreading fire in the face of 40-50 mph wind gusts near the foothills.

These fires have largely been a result of 1) the 5 yr extreme drought weakening trees 2) the very wet winter producing abundant brush growth 3) extreme hot, dry summer drying out all fuels.

New evacuation orders have already come out for some areas, including the City of Calistoga (northeast of Santa Rosa) where the entire town of over 5,000 are being told to leave. See the Impact Statement at the bottom of this post…but folks need to be ready to evacuate if necessary at a moment’s notice.

–Meteorologist Nick Humphrey

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CalFire has updated news at 11:30 am PDT and now say 21 people have been confirmed killed and 172,000 acres have now burned across the entire state. The most destructive fires are in North-Central California north of the Bay Area, but the Canyon 2 Fire continues to menace Anaheim in Southern California.

A RED FLAG WARNING is in effect for much of the interior valleys and foothill terrain of California.


This is for extreme fire danger today – Thursday. As high pressure builds this evening and tonight over Nevada and east of the Sierra Nevada Mountains, a NE-SW pressure gradient will intensify, leading to strong downslope winds known as Diablo winds or Santa Ana Winds (the former in Northern CA, the latter in Southern CA). These winds will gust potentially 40-45 mph+. In addition, because they are downsloping, the air undergoes adiabatic warming…warming caused by the air compressing as it flows down toward higher vertical pressure at lower elevations. The air not only warms, but also dries out, turning winds blasting out of canyons into a hot blow dryer…drying out fuels and allowing a fire to turn into a firestorm.

IMPACT STATEMENT:

I CANNOT STRESS ENOUGH…if you live in areas under the red flag warning or if you know anyone who lives in these areas, especially near the urban-wildland interface…please have a plan of what to do if a mandatory evacuation is ordered for your area and have a way to get warnings. ESPECIALLY AT NIGHT. Stay in contact with friends/relatives, have someone stay up to watch tv or listen to radio, keep your phone on and charged, have a weather radio. Most importantly, make sure those smoke detectors are working as they may be a final warning of danger impacting your home at night. These fires may intensify or new ones may start Wed night-Thurs morning because of strengthening winds and the humidity…which normally increases at night…may not do so because of the very dry nature of the winds. This will allow for potentially explosive fire behavior. And please, be smart with anything related to flammable materials and clear any brush away from your home if possible, to give you more time if a fire does approach.

I really hope the situation does not worsen significantly. Fires are scary events and incredibly destructive. Please be safe and be ready if you are in these areas.

I’ll have updates on this page throughout today and tonight.

–Meteorologist Nick Humphrey

 

Hurricane Nate and Dangerous Storm Surge Heading for the Northern Gulf Coast Saturday (Updated at 2 pm CDT)

Update at 2 pm CDT:

Hurricane Nate is likely to be a Cat 1 or 2 at landfall (thinking NHC forecast of 2 as high-end). It is leveling off based on current satellite presentation as well as air force reconnaissance observations. STORM SURGE REMAINS THE GREATEST HAZARD. The asymmetric structure…a product of Nate’s forward motion, may intensify/focus surge/battering waves from Mouth of Mississippi River to the MS/AL border. 9-11 ft surge with battering waves expected Mouth of Miss. River to MS/AL border as center passes nearby. 6-9 ft east to AL/FL border. Dangerous. High tide along Gulf Coast of MS around midnight, passage of center may be 8-10 pm CDT…partial enhancement could exacerbate flooding.

Probability of Cat 1 at initial landfall: 90%

Probability of Cat 2 at initial landfall: 10%

Landfall should be between 5-7 pm in far Southwest Louisiana.

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Hurricane Nate is headed for a likely landfall with the northern Gulf Coast of the US this evening. The hurricane is blasting north-northwestward very fast for a tropical cyclone…26 mph at the moment. This is under the influence of an approaching upper-level trough of low pressure which will eventually turn it northeastward after landfall. The system has continued to organize as expected over the warm waters (83-84 degrees F) and favorable low wind shear. The storm (at 10 CDT) is a Category 1 hurricane with maximum sustained winds of 90 mph with gusts to 110 mph.

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Visible imagery of Nate showing its rapid forward motion toward the coast.

The waters atmospheric and oceanic conditions should remain favorable for intensification up until landfall. Landfall is likely between 6-8 pm in far southwest Louisiana. My assessment based on this on trends, is that Nate is likely (65%) to make landfall as Category 2 (100-110 mph sustained) with a moderate chance (10%) to make landfall as a Category 3 (115 mph+), if more rapid intensification occurs during the next 7-8 hrs. There is also a 25% chance of a landfall as a Category 1.

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National Hurricane Center track forecast at 10 am CDT Saturday.

Heavy rainfall (lessened by the storm’s forward speed) is most likely over southern Mississippi into Alabama. Much of Louisiana will miss the worst of the storm, including New Orleans, however points east will face potentially significant surge. Surge may reach 7-11 ft along the mouth of the Mississippi River to the Mississippi/Alabama border; 6-9 ft from the MS/AL border to the AL/FL border, including Mobile Bay.

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Potential Storm Surge Flooding by Nate Saturday night. Orange and Red colors represent potential for 6-9+ feet of surge.

If you know anyone in these areas, please tell them to evacuate NOW!! This storm is moving FAST and storm surge will, BY FAR be the greatest danger from Nate. Far more than the wind or even inland flooding. I do have some concern that the combination of the relatively recent development of this system, its fast forward movement, and resulting shorter lead time, in addition to the system being relatively weaker in terms of maximum sustained winds that people may not leave or leave fast enough. People need to leave and be safe.

I will have updates when possible this afternoon and evening.

Start of October Drought and Climate Update

Nearly 14% of the Continental US is in at least moderate drought conditions right now. The most highly afflicted areas are over the northern tier states west of the Mississippi River…the Dakotas, Montana, Idaho, Washington and Oregon.

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There are scattered areas of drought and abnormally dry conditions across other parts of the country. However, an isolated area of severe to extreme drought has been hitting south-central Iowa for much of the summer and there are also areas of moderate drought developing over the the Desert Southwest and eastern Maine.

The level of dryness, particularly over Western North America has promoted a significant fire season, which continues at this time. British Columbia is having its worst fire season on record and the Western US is having an unexpectedly destructive fire season. This even after much of the region had a wet winter, showing that a significant period of dryness following well-grown fuels from a wet season can still lead to a major fire season. As of October 4, 2017, nearly record 8.5 million acres have been burned in the United States in 2017.* While below the 2015 record of 10.12 acres, it should be noted that anthropogenic climate change is increasing the risk of fire seasons in the US over 3 million acres and there has been a significant increase in fire seasons of 3 million acres or more since the turn of the century. 2017 may rank in the Top 3 for fire seasons (along with 2015 and 2012). Temperatures across the West were well-above normal or record levels over the summer. Various records for heat (as well as persistence of warmth and dryness) were broken in places such as Western WA/OR, central and southern CA as well as the portions of the Interior West.

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Drought Outlook for October 2017. Drought is expected to dissipate in Western WA from the incoming wet season, and improve somewhat in northeast MT. However, much of the drought in the US will persist and in fact additional areas may develop over the central Midwest and Mid-Atlantic states.
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The Probabilistic Precipitation Outlook valid Oct 10-16, 2017. This suggest by mid-month, the atmospheric pattern will be favorable for drier than normal conditions over the center of the nation with near normal or wetter than normal conditions over the coastal regions. The Climate Prediction Center also shows above normal temperatures likely over the Southwest US and Eastern third of the country. Dryness will maintain or promote further development of drought conditions in portions of the nation’s interior.

As of today, the NWS Climate Prediction Center indicates a 55-60% chance that a La Nina climate pattern will develop late in the Northern Hemisphere Fall and into the Northern Hemisphere winter. This is characterized by an intensified Walker Circulation (the east-west tropical Pacific wind circulation) and intensified cold water upwelling along and offshore the coast of South America.

Weather patterns common during La Nina events include abnormally wet, cool conditions in the western Pacific Northwest and TN/OH valleys, but abnormally dry and warm conditions across the southern tier of the United States. This is partially incorporated into the monthly and seasonal drought and temperature/precipitation outlooks.

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For those curious, the climate models are showing the US having a more than likely above normal winter throughout (including AK) with the La Nina-like distribution of precipitation (likely above normal Northwest, below normal Southeast). More on winter as we get closer.

*-I incorrectly stated that total acres burned in the US was around 3 million acres. (10/4/17)

Update on Hurricane Maria (2:30 pm EDT). High winds and flooding rains impacting Puerto Rico.

Hurricane Maria is beginning to emerge from the island of Puerto Rico after the center made landfall 8 1/2 hrs ago as a Category 4 storm with max winds of 155 mph (Cat 5 is 156+ so catastrophic wind speeds occurred). 

The hurricane is now a Category 3 storm with 115 mph sustained winds and gusts over 130 mph near the center. Damaging winds and torrential flooding rains will continue for the rest of the afternoon as the system continues to push out into open ocean water.


Most computer models indicate the system should remain offshore the United States as it moves north in a weakness in the upper level higher pressure field caused by the presence of Tropical Storm Jose offshore the Mid-Atlantic and southern New England.

 
The crucial timing to be rid of Maria forever will be the approach of a significant upper level trough of low pressure from the Midwest midweek next week to “kick” the dying hurricane out to sea. Most models show this connection keeping the system offshore being, however there is higher variability in the track after Monday which could bring the system closer to shore than expected. Currently, I feel direct impacts…the tropical storm force wind field and significant rain bands…will likely (66%+ probability) stay offshore. But potential variability makes the situation worth watching closely. 

Regardless, high surf and rip currents (currents which pull water offshore and make swimming dangerous) are likely by early next week. The system will also be weaker offshore the East Coast thanks to less intense sea surface temperatures and increasing vertical wind shear from mid-latitude winds.

In the meantime, direct impacts from a Cat 3-4 storm are likely for north coast of the Dominican Republic, the Turks and Caicos Islands and the southern Bahamas. Hurricane warnings are in effect for all these areas. 

–Meteorologist Nick Humphrey

Update on Hurricane Maria (9:25 am EDT). Catastrophic flash flood/violent wind event ongoing.

Maria made landfall as a powerful Category 4 storm near Yabucoa, PR with maximum sustained winds of 155 mph and minimum central pressure of 917 millibars (at 6:35 am EDT). The hurricane continues to move across the island delivering destructive hurricane force winds and torrential amounts of rain leading to massive flash flooding (including 5-7 inch/hr rainfall rates).

The storm currently has max winds of 145 mph. 

River gauges across PR are rising incredibly fast from the high rainfall rates:


Radar near time of landfall (currently offline):