788
FXUS66 KSTO 160806
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
106 AM PDT Tue Jul 16 2024

.SYNOPSIS...
Slightly cooler weather is expected today and Wednesday, with Minor
to Moderate HeatRisk over the region. Temperatures begin to trend up
again later in the week and over the weekend.

&&

.Key Points...

- Slightly cooler today and Wednesday; warming trend expected by
  the weekend and into early next week.
- Potential for isolated mountain thunderstorms returns late in
  the weekend/early next week.

&&

.Discussion...
The last dregs of monsoonal moisture can be seen leaving area on
GOES satellite imagery tonight, so little if any chances remain for
isolated thunderstorms in the mountains over the next few days. Weak
troughing along the coast and the subsequent onshore flow it brings
will continue the slightly cooler and near normal temperatures
through Wednesday. Highs today and tomorrow will be in the low to
high 90s in the Valley, mid 80s to mid 90s in the foothills, and
high 70s to low 90s in the mountains.

Thursday and Friday warm up again slightly (though right now it
looks like it won`t be nearly to the degree we saw with the last
heat event) as upper level ridging reamplifies near the Four Corners
region late in the week and pushes back west. Widespread Moderate
HeatRisk with some isolated areas of Major HeatRisk are expected to
return starting Thursday. Right now, the probability of temperatures
reaching 100 or higher through the end of the week remain mostly
limited to areas where 100 is the normal temperature this time of
year, i.e. the northern Sacramento Valley (65-95% probability of
reaching or surpassing 100 degrees). However, there is a non-zero
chance (10-55% probability) of areas in the southern Sacramento and
northern San Joaquin Valleys also reaching 100 on Thursday or
Friday.

&&

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...
As the upper level riding over the four corners continues to
trend westward, chances for temperatures reaching or surpassing
100 degrees increase across the area over the weekend and early
into next week. By Monday and Tuesday, most Valley locations see a
75 to 95% probability of reaching 100 degrees or more, while
foothills locations can expect a 30 to 75% probability of this
occurring. Sunday and Monday also may see the return of some
monsoonal moisture, with the NBM showing a 10 to 20% probability
of isolated thunderstorms along the Sierra crest those days,
primarily south of I- 80. Confidence is low at this point but we
will be continuing to monitor the progression of any monsoonal
moisture into the area and the chance for thunderstorms it may
bring.

&&

.AVIATION...
VFR conditions next 24 hrs. Surface wind gusts generally under 12
kts except local southwest gusts up to 30 kts vicinity west
Delta, and areas of southerly/southwesterly gusts 20-30 kts
Sacramento Valley and northern Sierra 21Z until about 03Z
Wednesday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$