774
FXUS66 KMTR 081718
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
918 AM PST Sat Feb 8 2025

...New AVIATION...

.SYNOPSIS...
Issued at 1207 AM PST Sat Feb 8 2025

Mostly clear skies and cold mornings will persist through early next
week. The colder inland areas will drop below freezing each night.
An atmospheric river will bring significant rain from Wednesday-
Thursday.

&&

.UPDATE...
Issued at 857 AM PST Sat Feb 8 2025

This morning`s frost and freeze products are allowed to expire at
9AM. No other changes to the forecast were made at this time.

&&

.SHORT TERM...
(Today and tonight)
Issued at 1207 AM PST Sat Feb 8 2025

The GOES West night fog product shows mostly clear skies across the
Bay Area, with some patches of stratus over the Central Coast. The
clear skies are allowing enhanced radiational cooling, and
several inland areas are already in the 30s. As the temperature
drops to the dew point, the rate of cooling will likely slow
through the morning, although the air mass is also on a drying
trend, so this moderating effect won`t be as pronounced as
normal. Overall the observed temperature is matching the hourly
forecast well and the frost/freeze products remain unchanged.
After the sun comes up, the clear skies will allow temperature
will begin to climb, but we`ll only reach the mid-50s this
afternoon for most populated areas. Higher terrain won`t get out
of the 40s.

&&

.LONG TERM...
(Sunday through Friday)
Issued at 1207 AM PST Sat Feb 8 2025

Why is it getting so cold? After all the deep air mass isn`t that
cold. The 850 mb temperature is only in the 10-25th percentile
this weekend. This cooling is driven more by dry air supporting
enhanced radiational cooling. As the surface dew points drop into
the 20s-30s under clear skies, there is nothing to slow down
nocturnal cooling. Lower level winds will shift to light offshore
Sunday, causing the air mass to dry further. The PWAT looks very
likely to drop below 0.2", which is in the bottom 2% for
February. This very dry air mass will continue to support clear
skies and very cold mornings through early next week. Sunday and
Monday look to be the coldest. Our official forecast brings
downtown San Francisco to 39 Monday morning. That mark is roughly
10 degrees below normal, and has only been reached 3 times in the
last decade (2/23/23, 2/24/23, 3/1/23). Meanwhile San Jose has a
60% chance of dropping below freezing for the first time since
2017.

Everything changes on Wednesday. The winds will shift from
northerly to southerly as low pressure system moves over the
Pacific Northwest. An associated warm front and cold front will
both push through California, bringing a prolonged period of
moderate to occasionally heavy rain that will linger into Friday.
The heaviest period currently looks to be from late Wednesday
through late Thursday, when 1-3" of rain is expected in the
lowlands with more in the coastal mountains. This will likely
cause some flooding issues for urban environments and smaller
streams. The USGS has also informed us that soil moisture sensors
are indicating shallow landslides are likely if the rain rates get
high enough. This system will also bring some wind, though with
the actual low pressure center much further north than the most
recent storm, the pressure gradient and wind potential are
somewhat lower. Things currently look to dry out Friday before a
dry weekend, but that`s not a guarantee as the uncertainty remains
high.

&&

.AVIATION...
(18Z TAFS)
Issued at 917 AM PST Sat Feb 8 2025

High confidence VFR through the TAF period for most terminals
except KLVK, where LIFR conditions continue. Fog should clear up
shortly after 18Z. Winds will remain relatively light to moderate
through the TAF period.

Vicinity of SFO...High confidence VFR with light to moderate winds
through the TAF period.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the TAF period. Winds will have
southerly direction overnight. but speeds will remain mostly light
to moderate through the TAF period.

&&

.MARINE...
(Today through Thursday)
Issued at 857 AM PST Sat Feb 8 2025

Strong northerly winds will prevail through Tuesday with the bays
remaining sheltered from the strongest gusts. Significant wave
heights will remain in the moderate to rough realm. An approaching
low will bring rain Tuesday night through Friday morning.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Frost Advisory from 1 AM to 9 AM PST Sunday for CAZ502>504-508-
     510-512-513-528>530.

     Freeze Warning from 1 AM to 9 AM PST Sunday for CAZ506-514>518.

PZ...Small Craft Advisory until 3 AM PST Sunday for Pigeon Pt to Pt
     Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to
     Pigeon Pt 0-10 nm.

     Small Craft Advisory until 9 PM PST Sunday for Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

     Small Craft Advisory until 9 AM PST Monday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...SO
MARINE...SO

Visit us at www.weather.gov/sanfrancisco

Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea

NWS MTR Office Area Forecast Discussion

// settings:
//  change myNWS to abbreviation for your local NWS office
//    other settings are optional
//
    $myNWS = 'MTR';   // San Francisco, NWS office
//  $myNWS = 'PQR';   // Portland, OR
//  $myNWS = 'OAX';   // Omaha, NE (Carter Lake, IA)
//

$cacheName = "forecast-discussion.txt";  // used to store the file so we don't have to
//                          fetch it each time
$refetchSeconds = 1800;     // refetch every nnnn seconds

$cacheFileDir = './';      // default cache file directory

// end of settings

<?php
include_once("worldextremes.php");

print "<p>USA Extremes for $reportDate</p>\n";
print "<p>High Temperature<br/><br/>$usahigh</p>\n";
print "<p>Low Temperature<br/><br/>$usalow</p>\n";
print "<p>High Precipatation<br/><br/>$usaprecip</p>\n";
print "<p><small>Data courtesy of <a href=\"";
print "https://www.cpc.ncep.noaa.gov/products/cadb/";
print "\">NWS-CPC</a></small></p>\n";

?>

USA Extremes for Friday, February 7, 2025

High Temperature

95°F at Fort Stockton Pecos County Ap, TX

Low Temperature

-17°F at Malta, MT

High Precipatation

0.79in at Blue Canyon Nyack Ap, CA

Data courtesy of NWS-CPC

$cacheFileDir = './'; // directory to store cache file in.
$cacheFile2 = "worldextremesCache.txt";  
// Age of cache file before re-fetch caching time, in seconds (3600 = 1 hour)
$cache_life = '3600';
$reportDateFormat = "l, F j, Y"; // Day, Month d, yyyy 
$tUOM = '°F'; // or ='' for no temperature unit display (display in C is default)
$rUOM = 'in';     // or ='' for no rain unit display (display in mm is default)
#
$ignoreCountrys = array('Antarctica','Greenland');     // for world extremes - exclude these country(s)
$ignoreStations = array('99KLRJ');     // list of stn_id (field 0) to ignore for bogus data
$tempDiffAllowed = 40; // max difference Tmax-Tmin (C) for valid data
$selectedCountry = 'Canada'; // for country max/min/precip in $country* variables
// note: the $usa* variables will have the min/max/precip for the lower-48 states
$selectedState   = 'CA';  // for USA state max/min/precip in $state* variables