Altadena, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

708
FXUS66 KMTR 021809
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1109 AM PDT Wed Apr 2 2025

...New AVIATION...

.SYNOPSIS...
Issued at 203 AM PDT Wed Apr 2 2025

Warming and drying trend kicks off today with the return of above
seasonal normal temperatures and minor HeatRisk by Friday.

&&

.UPDATE...
Issued at 900 AM PDT Wed Apr 2 2025

Skies are generally clear across the region with some clearing
stratus in the eastern Santa Clara Valley and the higher
elevations of the Central Coast. Drier conditions will prevail
today, and a warming trend starts today with the inland valleys
reaching the lower to middle 60s. The downtown San Francisco site
reach a low of 46 this morning, three degrees above their daily
minimum low temperature of 43. No changes to the forecast.

DialH

&&

.SHORT TERM...
(Today and tonight)
Issued at 203 AM PDT Wed Apr 2 2025

KMUX continues to show isolated rain and snow showers, primarily
across the Central Coast. This activity will continue to diminish
over the next few hours as the responsible surface low pressure
system continues to drift southeastward. While today will begin the
warming and drying trend, it may not necessarily feel like it with
the 00Z OAK sounding showing a -0.75 degrees Celsius temperature at
850 millibars, this is below the 10th percentile for April 2nd. San
Francisco Downtown (SFOC1) is actually forecast to come within two
degrees of their daily record low for today (this morning), the
official forecast is 45 degrees and the current record is 43 degrees
in 1955. Records or not, cold conditions can be expected in the
higher terrain as skies clear and winds diminish, promoting maximal
radiational cooling. Dry conditions and temperatures several degrees
below normal are on tap for today.

&&

.LONG TERM...
(Thursday through Tuesday)
Issued at 203 AM PDT Wed Apr 2 2025

Warming trend continues Thursday, but widespread below normal
temperatures and cold conditions in the higher terrain continue to
be expected. Three climate sites daily low temperatures will be in
jeopardy Thursday morning: San Rafael (SARC1) forecast is 41 degrees
with a previous record of 39 degrees in 2010, San Francisco Downtown
(SFOC1) forecast is 44 degrees with a previous record of 41 degrees
in 2001, and Oakland Museum (OAMC1) forecast is 44 degrees with a
previous record of 43 degrees in 2003. Friday is when the sensible
weather will feel noticeably warmer with the return of above
seasonal normal temperatures and even minor HeatRisk. Global
ensemble clusters are in excellent agreement through Saturday with
an upper-level longwave ridge building into the West from the
Eastern Pacific Ocean. A cold front will try and dampen the warming
and drying party, but it`s impacts are largely only expected to be a
brief pause in the warming trend and rainfall totals of only a few
hundredths in the North Bay. Warming and drying trend resumes
Tuesday with the Climate Prediction Center indicating a 60-70%
probability that temperatures will be above normal April 7th-11th.

&&

.AVIATION...
(18Z TAFS)
Issued at 1055 AM PDT Wed Apr 2 2025

VFR is expected to prevail through the forecast period with a
chance of MVFR stratus developing overnight for KSNS and KMRY.
Gusty afternoon winds along coastal terminals will persist
through the early evening and gradually ease after sunset.
Confidence in the potential for MVFR ceilings developing is
low attm.

Vicinity of SFO...VFR with breezy onshore flow.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Gradual improvement through 14-16Z with
VFR this afternoon. Lower confidence of evening cigs for KMRY.
Current taf shows VFR, but some guidance hints at bringing shallow
cigs back by 04Z.

KMRY and KSNS MVFR ceilings are expected to mix out by 19Z this
afternoon, and remain VFR for the remainder of today and tonight.
Short term guidance suggests the potential for MVFR ceilings to
develop after sunset, but confidence is low attm. Breezy winds
will ease after sunset with continues onshore flow expected
through the TAF period.

&&

.MARINE...
(Today through Monday)
Issued at 900 AM PDT Wed Apr 2 2025

High pressure will continue to build in offshore with breezy
north/northwest flow over the coastal waters continuing through
early Thursday. Hazardous conditions continue today and tonight,
however waveheights will gradually ease through Thursday morning.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 PM PDT this afternoon for Mry Bay.

     Small Craft Advisory until 3 AM PDT Thursday for Pigeon Pt to Pt
     Pinos 0-10 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.

     Small Craft Advisory until 9 PM PDT Thursday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...JM
MARINE...JM

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