National Weather Service United States Department of Commerce

Massive Heat Wave; Severe Storms and Heavy Rain

A massive heat wave is consuming much of the Midwest into the Southern tier of the U.S. with hazy, hot and humid conditions. These dangerous conditions will likely persist through Thursday as widespread excessive heat warnings and heat advisories are in effect. North and east of the heat and area of high pressure, thunderstorms with damaging and severe winds, large hail and heavy rain are likely. Read More >

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000
FXUS66 KMTR 052113
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
213 PM PDT Tue Jul 5 2022

.SYNOPSIS...A mix of low and mid level clouds continue this
afternoon with the potential for drizzle along and near the
coast again tomorrow morning. A gradual warming and drying trend
begins by midweek, however, below normal temperatures persist
today through Friday for the afternoon highs. By Saturday, the
region warms back to near to slightly above normal conditions.

&&

.DISCUSSION...as of 02:07 PM PDT Tuesday...Observing widespread
areas of stratocumulus clouds via satellite and webcams this
afternoon. The low to mid levels of the atmosphere continue to have
a higher than usual moisture content thanks to the persistent upper
level low spinning off the coast of the Pacific NW. The 12z Oakland
sounding indicated that precipitable water (AKA PWAT values, which
helps to quantify how much water content is in the air) was 1.25
inches, which is around 200% of normal. At the surface, this has
translated to higher than normal dewpoints that range from lower to
upper 60s (with temperatures currently in the 70s to low 80s),
resulting in the air feeling muggy. Peak "mugginess" will likely be
today as a drier airmass moves in tonight/tomorrow and PWAT values
are forecast to decrease. Similar to this past morning, coastal
areas in the North Bay down to the San Mateo coast could see some
light drizzle again in the early morning hours Wednesday. Low clouds
and patchy fog also likely again overnight into Wednesday morning.
Wednesday during the day will see similar temperatures to today
(widespread 70s to low 80s).

By Thursday, this anomalous trough that has been parked over the
West Coast will begin to break down as high pressure starts to build
in from the desert Southwest. This pattern change will be a more
typical summer-like pattern for the region. With this pattern shift,
a warming trend will commence and more seasonable temperatures
across the CWA are expected (60s to 70s near the coast, 80s in the
interior). By the weekend, max temperatures will be toasty again
with interior regions reaching the low 90s. Heat Risk remains low
through Friday, but come Sunday/Monday interior regions will be at a
moderate level for heat risk, meaning sensitive populations should
use caution. While this warm up won`t result in temperatures in the
triple digits inland, the increase in temperatures region-wide still
worth emphasizing as temps have been below normal the last few days.

Looking further ahead, deterministic and ensemble long range models
are in agreement that this broad region of high pressure will
persist over much of the Western CONUS into mid July, so this
pattern change is likely here to stay for the foreseeable future.

&&

.AVIATION...as of 10:34 AM PDT Tuesday...For the 18Z TAFs.
Tuesday morning`s stratus clouds have provided quite the mess
across Bay Area terminals. Luckily, most cigs have recovered to
MVFR conditions. But pockets of dry area are utilizing the
southwest flow aloft and are mixing down changing BKN/OVC to SCT
for moments in time. More dry air will entrain down to the surface
to the late morning, with eventual widespread VFR clearing around
21Z. The onshore seabreeze will likely develop around 22Z. The
overarching weather remains generally the same so the forecast for
an early return of stratus is in the TAFs. Mostly MVFR
conditions, with much lower cigs for Monterey Bay terminals due to
the growing high pressure compressing the atmosphere.

Vicinity of KSFO...The terminals will likely continue to waffle
between SCT and BKN through around 21Z. VFR forecast for Tuesday
afternoon with a seabreeze through the San Bruno Gap. Another
early return for MVFR conditions overnight. With a chance for IFR
cigs early Wednesday morning. Cigs will gradually increase through
Wednesday as the onshore breeze returns.

KSFO Bridge Approach...Similar to SFO.

Monterey Bay...Surprisingly early clearing to VFR conditions, but
a thick layer of stratus around 5000 feet AGL sits over terminals.
Onshore seabreeze Tuesday afternoon. Winds will diminish in the
evening as IFR conditions return, slowly dropping to LIFR/VLIFR
levels for Wednesday morning. Clearing not expected until closer
to Wednesday`s 18Z TAF package.

&&

.MARINE...as of 02:12 PM PDT Tuesday...Winds over the waters
remain light to breezy and will continue as such through Wednesday
morning. Winds will increase along the immediate coastline south
of Pigeon Point and down the Big Sur coast Wednesday afternoon
which can cause hazardous seas for smaller craft. A 7 to 10
second west swell arrives Tuesday night while a longer period
southerly swell prevails through the late week. Winds increase
over the weekend for a return to a stronger wind-wave driven sea
state.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...NONE.

&&

$$

PUBLIC FORECAST: McCorkle
AVIATION: DK
MARINE: DK

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