Herndon, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

357
FXUS66 KHNX 161116
AFDHNX

Area Forecast Discussion
National Weather Service Hanford CA
416 AM PDT Wed Apr 16 2025

.UPDATE...
Aviation Section.

&&

.KEY MESSAGES...
1. Temperatures are expected to cool down today, with highs
approaching normal on Wednesday and slightly below normal on
Thursday. Warming begins again by Friday and will be back to
above normal by the weekend.

2. Breezy conditions are expected for the Mojave Slopes through
the week, peaking on Thursday.

3. There is a slight chance for showers and thunderstorms
across the Sierra Nevada each afternoon Tuesday through Friday.

4. There is a Marginal Risk (at least 5%) for excessive rainfall
in the Sierra Nevada on Wednesday.

&&

.DISCUSSION...
Current satellite imagery shows the build-up of cumulus clouds
across the Sierra Nevada crest, which have a 25 to 20 percent
chance of becoming proper thunderstorms later this afternoon.
Similar probabilities for thunderstorms become more widespread
across the Sierras tomorrow, with a 10 to 15% chance coming into
the foothills and the eastern San Joaquin Valley. These showers
and thunderstorms also have the chance to drop a significant
amount of rainfall for this time of year in the Sierras and the
adjacent foothills, with the WPC putting a Marginal Risk (5%)
of excessive rainfall in that region due to PWATs of 0.5 to
0.75. Keep in mind that these PWATs may seems light, but these
are well above normal for this time of year, and are even in the
95th percentile of average. This rainfall would also be falling
above 8000 feet onto a near normal amount of snowpack, so an
increase in stream flow from snowmelt would be impactful to the
downstream areas.

The trough that is bringing in all this moisture into the
region will continue to do so through Thursday, leading to
chances for thunderstorms each afternoon. Then, a second trough
is expected to drop down from Canada and may bring some
measureable precipitation to the Valley, as well as the Sierra
Nevada. There is currently a 30 to 55% chance for at least 0.25
inches of rain on the southeastern portion of the Sierra Nevada
on Friday, as the trough is expected to skim the southern
California/Nevada border that day.

After this trough moves to the east, a small ridge will build in
it`s place, leading to an increase in afternoon highs and a
return to above normal temperatures through this weekend. Long
term modeling shows the flow pattern may become more zonal in
the upcoming week, leading to near normal temperatures.

&&


.AVIATION...
12Z Update

A slight chance (10-20 percent) of afternoon thunderstorms
across the Sierra Nevada and Foothills from 18Z Wednesday
through 06Z Thursday. Otherwise, VFR Conditions will prevail
over the Central California Interior with a 40-60 percent chance
of MVFR Ceilings near the Grapevine (south of KBFL) after 16Z
Wednesday.

&&

.AIR QUALITY ISSUES...
None.

&&

.CERTAINTY...

The level of certainty for days 1 and 2 is high.
The level of certainty for days 3 through 7 is medium.

Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.html for additional information
and/or to provide feedback.

&&


.HNX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

aviation....Proton

weather.gov/hanford