Hot and dry conditions increased wildfire danger in late August, with the Ponderosa Wildfire starting on August 29th and continuing into September.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS STO wrote it up.
Hot and dry conditions increased wildfire danger in late August, with the Ponderosa Wildfire starting on August 29th and continuing into September.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Sacramento, CA wrote its last area forecast discussion before the first event at Aug 29, 9:05 AM PST, 3 hours 11 minutes earlier.
Area Forecast Discussion
National Weather Service Sacramento CA
1005 AM PDT Tue Aug 29 2017
.SYNOPSIS...
Not quite as hot today and Wednesday, then very hot weather
returns with record highs possible later in the week and through
the Labor Day Holiday weekend. Slight chance of late-day
thunderstorms over the Sierra Nevada south of Lake Tahoe through
Wednesday.
&&
.DISCUSSION...
Incoming Pac trof will weaken the ridging over Norcal enough to
provide a brief respite of relief from the heat today and Wed.
Marine layer has deepened to about 1800 ft and with an increase in
onshore gradients (over 3 mbs) and the Delta Breeze has returned. 24
hr temp change indicates as much as 10 degrees of cooling in the
Delta/Carquinez Strait area. Hourly LAMP guidance suggests the
forecast maxes today are too high in the Delta influenced areas and
will monitor the trend for a possible update later this morning. Sac
area temps may range from 95 to 100 instead of the low 100s forecast
earlier.
Very subtle wave moving through the SWly flow between the Wwd drift
of the 4-Corners High and the incoming trof is producing some clouds
over Stanislaus Co Ewd and light showers over SErn Tuolumne Co. This
should continue to lift NEwd today but we can't rule out a possible
T-storm near the Crest south of Alpine Co this afternoon. Afternoon
thunder possible again Wed afternoon roughly in the same area as the
upper trof nears the region. JHM
.Previous Discussion (with some added info)...
Another extended period of record heat is forecast to commence later
this week as strong high press another heat wave is suggested in the
anomaly data and upper air pattern late in the week (Fri) and into
long Labor Day Holiday weekend. Very hot wx returns to Norcal as a
595+ Ern Pac ridge builds inland on Thu and then phases with the
Great Basin/4-Corners High over the weekend. A strong 850 mbs
anomaly from the NAEFS suggests record heat possible in the Srn Sac
and Nrn San Joaquin Vly with a return interval of once every 5-10
yrs over much of the interior Valley of Norcal Fri and Sat, then
weakening Sun/Mon to a 2-5 yr anomaly. Guidance temps probably
trending back towards climo then, but with the synoptic charts
maintaining a very strong Great Basin High (at times 597-598 dam)
and extending it into Norcal until the end of the EFP, we don't see
a significant end to the heat wave during this forecast period.ure
from the eastern Pacific moves over the area and phases with the 4-
Corners High which is still forecast to be displaced slightly
farther to the west and giving Norcal even hotter wx. Widespread 110-
115 max temps possible by Friday in the valley with light northerly
flow and 850 mb temps climbing to around 30-32C.
The NAEFS temp return intervals for Fri and Sat show a 1 in every
10+ year event (think of it as a decade of more event), moderating
to a 1 in every 5-10 yrs Sun and one in every 2-5 yrs Mon. This
would signal some impressive (possibly record-breaking) heat is
likely Fri/Sat. An excessive heat watch has been issued.
See table below for record highs.
RDD RBL DTS SAC SCK MOD
Aug 28 109(2008) 110(2008) 105(1915) 104(2008) 106(1981) 105(2015)
29 109(1988) 112(1944) 108(1987) 105(2007) 108(2007) 107(2008)
30 110(1987) 110(1968) 110(1987) 107(1968) 105(2007) 106(1988)
31 111(1987) 109(1998) 108(1976) 104(1998) 103(1958) 104(2007)
Sep 1 110(1998) 114(1950) 109(1950) 108(1950) 105(1952) 105(2007)
2 112(1998) 112(1950) 109(1955) 108(1955) 108(1950) 106(1955)
3 116(1988) 117(1988) 108(1955) 108(1955) 107(1955) 105(1955)
4 115(1988) 118(1988) 108(1988) 108(1988) 105(1988) 105(1988)
&&
.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)
Heat continues in earnest for the holiday weekend as strong
ridging remains entrenched across the West Coast. Ensemble
guidance shows max percentiles for heights and temperatures which
should lead to daytime highs 15 to 20 degrees above normal with
some daily records likely falling. Overnight lows will remain
rather warm as well with limited relief from the heat overnight.
Have bumped up temperatures a few degrees from previous forecast
in line with model trends. Excessive Heat Watch has been issued
through Monday. Outdoor events for Labor Day Weekend will be
impacted with a high risk for heat-related illnesses for much of
the population, not just sensitive groups. Guidance shows ridge
persisting for the foreseeable future with heat continuing into at
least the middle next week, though perhaps not quite as hot as
the weekend.
GFS shows some moisture surging northward under the ridge with a
chance for mountains showers and thunderstorms by Sunday afternoon
and Monday while ECMWF suppresses moisture further south. Not
sure how widespread activity will be with such strong ridging in
place, but have low chances for thunderstorms along the Sierra
crest for Sunday, Monday, and Tuesday afternoons. This would
increase concerns for fire starts with any activity given very
hot temperatures and dry fuels.
CEO
&&
.AVIATION...
VFR conditions through the period. A few gusts to 20 kts across
northern Sac Valley this afternoon with gusts to 30kt invof the
Delta.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Watch from Thursday afternoon through Monday
evening for Burney Basin / Eastern Shasta County-Carquinez
Strait and Delta-Central Sacramento Valley-Clear Lake/Southern
Lake County-Motherlode-Mountains Southwestern Shasta County to
Northern Lake County-Northeast Foothills/Sacramento Valley-
Northern Sacramento Valley-Northern San Joaquin Valley-Shasta
Lake Area / Northern Shasta County-Southern Sacramento Valley-
West Slope Northern Sierra Nevada-Western Plumas County/Lassen
Park.
&&1 wildfire. Local standard time, as filed.
The Ponderosa Fire burned 4,016 acres and destroyed 54 structures, 32 homes & 22 outbuildings. There were 2 injuries. The fire cause was an illegal campfire that got out of control.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2017Every state in 2017This day in weather historyWarnings in California, August 2017
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 711896.