Morgan Hill, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

958
FXUS66 KMTR 200335
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
835 PM PDT Mon May 19 2025

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 154 AM PDT Mon May 19 2025

Elevated fire weather conditions today for far interior portions
of the East Bay, South Bay, and Central Coast. Strong northerly
winds and above normal temperatures continue today with hazardous
marine conditions lingering through Tuesday.

&&

.SHORT TERM...
Issued at 212 PM PDT Mon May 19 2025
(This evening through Tuesday)

Key Messages
-Shallow marine layer returns
-Breezy to gusty northerly flow
-Elevated fire weather concerns

No major changes in the long wave pattern over the region the past
24 hours. However, details underneath have. High pressure aloft and
at the surface continues to be the driver for sensible weather.
Sunny skies prevail again this afternoon, but as the N-S gradient
begins to ramp up this afternoon one can see a shallow marine
layer reforming. In fact, if one looks closely at the visible
satellite imagery you`ll notice standing wave clouds forming along
the coastal terrain features sticking out in the NW flow (like Pt
Reyes). So what does all this mean for the forecast? Coastal
waters and coastal areas will see an influx of low clouds this
afternoon and tonight. Winds will also increase with strongest
winds over the waters, coastal areas, and terrain features inland
oriented NW to SE (Santa Clara/Salinas Valleys). Lastly, since
we`re still around peak heating time there is still a concern for
elevated fire weather conditions. There have been a handful of
smaller veg fires the last few days and today is no different.

Generally speaking Tuesday will be more of the same: just a tad
warmer and drier, especially inland. Tuesday morning will feature
a few more marine layer clouds than Monday morning.

&&

.LONG TERM...
Issued at 240 PM PDT Mon May 19 2025
(Tuesday night through next Sunday)

Key Messages
-Warming and drying through Wednesday
-Cooler, but dry weather returns Thursday and beyond

The peak of the warm up is still focused on Wednesday as high
pressure is at its strongest. Have nudged temperatures slightly
warmer across the interior as they`ll have the least amount of
influence from the onshore flow and cooler SST. Warmest locations
will easily be in the 90s with interior Monterey making a run for
100 degrees. Given the warmer temperatures HeatRisk values will
creep up to the Moderate category, but most of the forecast area
remains in the Minor category.

Finally, a shift in the long wave pattern late Wednesday into
Thursday. The high pressure ridge flattens and sinks southward as
an upper level trough sweeps through NorCal/OR. The initial
passing of this feature will kick off a cooling trend. To enhance
the cool trend, a deeper and more broad upper trough moves through
CA as we head into the weekend. Seasonably cool temperatures will
develop and persist into next weekend. Despite these passing
features the forecast remains dry the next seven days (outside of
coastal marine drizzle).

&&

.AVIATION...
(06Z TAFS)
Issued at 835 PM PDT Mon May 19 2025

It`s VFR over land except patches of stratus and fog /LIFR-IFR/
are developing along the immediate coastline. Late afternoon and
early evening satellite imagery showed standing waves within the
stratus and fog.

The ACV-SFO pressure gradient is 7.2 mb, the UKI-STS pressure
gradient is strong at 2.6 mb, the onshore gradient SFO-SAC is 2.7
mb. Pressure gradients initiate atmospheric motion; the overall
pressure pattern in recent days has favored gusty northwest winds
over the coastal waters and gusty west winds across the San
Francisco Bay, this is common during spring and even early summer
seasons. The marine layer varies in depth from several hundred
feet to locally up over 1500 feet e.g. Fort Ord profiler.

A general convergence of higher dewpoint air (water vapor) in
contact with chilly sea surface temps 50F-55F trapped beneath the
lower level temperature inversion ahead of overnight cooling both
due to temperature advection and radiative cooling to space favor
additional stratus and fog /LIFR-IFR/.

Vicinity of SFO...Strong west wind continuing through the evening,
with gusts 35-40 knots up through midnight. Increasing convergence
of stratus and fog on the ocean side of the peninsula will likely
advect on westerly wind reaching SFO late tonight and early Tuesday
morning, a dry surface based cold front will move southward along
the coast temporarily moving the stratus inland to the terminal
before drier post frontal air moves in for early return to VFR
Tuesday. West wind increasing to 20 to 30 knots with possibly higher
gusts Tuesday afternoon and evening. Current HREF output shows VFR
for Tuesday night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...It`s currently VFR, however expect an
increasing probability of stratus with patchy fog /LIFR-IFR/ with
onshore winds 10 to 20 knots during the evening. Expect LIFR-IFR
in stratus, fog including possibly a few patches of late night
and/or morning drizzle tonight and Tuesday morning. Conditions
improving to VFR by late Tuesday morning and early afternoon.
Onshore winds 10 to 20 knots Tuesday afternoon and early evening.

&&

.MARINE...
(Tonight through next Sunday)
Issued at 810 PM PDT Mon May 19 2025

Surface high pressure will result in widespread strong northerly
gale force gusts over the inner and outer waters through Tuesday.
Hazardous seas will persist Wednesday through Friday with strong
northwesterly winds occasionally near gale force gusts.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Tuesday for SF Bay N of Bay
     Bridge.

     Small Craft Advisory until 9 PM PDT Tuesday for Mry Bay.

     Gale Warning until 9 PM PDT Tuesday for Pigeon Pt to Pt Pinos 0-
     10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-
     10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to
     Pigeon Pt 0-10 nm.

     Gale Warning until 3 AM PDT Wednesday for Pt Arena to Pt Reyes
     10-60 NM.

&&

$$

SHORT TERM...MM
LONG TERM....MM
AVIATION...Canepa
MARINE...Canepa

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