Alert archive / California / Heat Advisories in 2021
Heat Advisory 1, NWS San Francisco Bay Area, CA
NWS San Francisco Bay Area, CA issued this heat advisory at May 28, 2021, 12:41 PM PDT for 5 counties in California. It took effect at May 31, 2021, 12:00 PM PDT. It was in force for 9 hr.
The area
The counties it named.
The facts
- Issued
- May 28, 2021, 12:41 PM PDT (19:41 UTC)
- In effect from
- May 31, 2021, 12:00 PM PDT
- Expired
- May 31, 2021, 9:00 PM PDT
- In force
- 9 hr
- Issued by
- NWS San Francisco Bay Area, CA
Counties Alameda County, CA, Contra Costa County, CA, Marin County, CA, Napa County, CA, Sonoma County, CA
The radar
The Sacramento radar (KDAX), 73 km from the middle of the area, began a volume at 19:44 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Oakland, CA (KOAK), launched 12:00Z, 7.7 hours before the alert went out and 47 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 1 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 581 m above ground
- 0-6 km bulk shear
- 18 kt
- 0-1 km storm-relative helicity
- 63 m²/s²
- 0-3 km storm-relative helicity
- 68 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
692 WWUS76 KMTR 281941 NPWMTR URGENT - WEATHER MESSAGE National Weather Service San Francisco Bay Area 1241 PM PDT Fri May 28 2021 CAZ506-507-510-511-290500- /O.NEW.KMTR.HT.Y.0001.210531T1900Z-210601T0400Z/ North Bay Interior Valleys-North Bay Mountains- East Bay Interior Valleys-East Bay Hills and the Diablo Range- Including the cities of Santa Rosa, South Santa Rosa, Napa, San Rafael, Petaluma, Novato, Rohnert Park, Angwin, Lagunitas-Forest Knolls, Woodacre, Concord, Antioch, Livermore, Walnut Creek, Pleasanton, Pittsburg, San Ramon, and Blackhawk 1241 PM PDT Fri May 28 2021 ...HEAT ADVISORY IN EFFECT FROM NOON TO 9 PM PDT MONDAY... * WHAT...Hot temperatures expected Monday in the low 90s to low 100s F in the interior North Bay and East Bay. Sea breeze will keep temperatures along the coast and bay in the 80s and low 90s. Overnight lows will be in the 60s and 70s in the hills, so expect little relief. These will be some of our hottest temperatures of the year thus far. * WHERE...North Bay Interior Valleys, North Bay Mountains, East Bay Interior Valleys and East Bay Hills and the Diablo Range. * WHEN...From noon to 9 PM PDT Monday. * IMPACTS...Increased risk of heat related illnesses such as heat exhaustion and heat stroke can occur due to prolonged exposure to hot temperatures. People most vulnerable include those who spend extended periods outdoors, those without air conditioning, young children, the elderly, and those with chronic illness. * ADDITIONAL DETAILS...Those seeking relief at area beaches should be mindful of cold water temperatures and dangerous rip currents. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ For more information from the National Weather Service visit http://weather.gov/mtr
9 follow-up statements
215 WWUS76 KMTR 290442 NPWMTR URGENT - WEATHER MESSAGE National Weather Service San Francisco Bay Area 942 PM PDT Fri May 28 2021 CAZ506-507-510-511-291245- /O.CON.KMTR.HT.Y.0001.210531T1900Z-210601T0400Z/ North Bay Interior Valleys-North Bay Mountains- East Bay Interior Valleys-East Bay Hills and the Diablo Range- Including the cities of Santa Rosa, South Santa Rosa, Napa, San Rafael, Petaluma, Novato, Rohnert Park, Angwin, Lagunitas-Forest Knolls, Woodacre, Concord, Antioch, Livermore, Walnut Creek, Pleasanton, Pittsburg, San Ramon, and Blackhawk 942 PM PDT Fri May 28 2021 ...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TO 9 PM PDT MONDAY... * WHAT...Hot temperatures expected Monday in the low 90s to low 100s F in the interior North Bay and East Bay. Overnight lows will be in the 60s and 70s in the hills, so expect little relief. These will be some of our hottest temperatures of the year thus far. Sea breeze will keep daytime highs along the coast and bay in the 80s and low 90s. * WHERE...North Bay Interior Valleys, North Bay Mountains, East Bay Interior Valleys and East Bay Hills and the Diablo Range. * WHEN...From noon to 9 PM PDT Monday. * IMPACTS...Increased risk of heat related illnesses such as heat exhaustion and heat stroke can occur due to prolonged exposure to hot temperatures. People most vulnerable include those who spend extended periods outdoors, those without air conditioning, young children, the elderly, and those with chronic illness. * ADDITIONAL DETAILS...Those seeking relief at area beaches should be mindful of cold water temperatures and dangerous rip currents. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ For more information from the National Weather Service visit http://weather.gov/mtr
669 WWUS76 KMTR 291241 NPWMTR URGENT - WEATHER MESSAGE National Weather Service San Francisco Bay Area 541 AM PDT Sat May 29 2021 CAZ506-507-510-511-300500- /O.CON.KMTR.HT.Y.0001.210531T1900Z-210601T0400Z/ North Bay Interior Valleys-North Bay Mountains- East Bay Interior Valleys-East Bay Hills and the Diablo Range- Including the cities of Santa Rosa, South Santa Rosa, Napa, San Rafael, Petaluma, Novato, Rohnert Park, Angwin, Lagunitas-Forest Knolls, Woodacre, Concord, Antioch, Livermore, Walnut Creek, Pleasanton, Pittsburg, San Ramon, and Blackhawk 541 AM PDT Sat May 29 2021 ...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TO 9 PM PDT MONDAY... * WHAT...Hot temperatures expected Monday. Forecast highs from the 90s to 105 F in the interior North Bay and East Bay. Overnight lows will be in the 60s and 70s in the hills, so expect little overnight relief. These will be some of our hottest temperatures of the year thus far. Sea breezes will keep daytime highs close to the ocean in the 70s, and in the 80s and lower 90s near San Francisco Bay. * WHERE...North Bay Interior Valleys, North Bay Mountains, East Bay Interior Valleys, and East Bay Hills and the Diablo Range. * WHEN...From noon to 9 PM PDT Monday. * IMPACTS...Increased risk of heat related illnesses such as heat exhaustion and heat stroke can occur due to prolonged exposure to hot temperatures. People most vulnerable include those who spend extended periods outdoors, those without air conditioning, young children, the elderly, and those with chronic illness. * ADDITIONAL DETAILS...Those seeking relief at area beaches should be mindful of cold water temperatures and dangerous rip currents. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ For more information from the National Weather Service visit http://weather.gov/mtr
226 WWUS76 KMTR 300435 NPWMTR URGENT - WEATHER MESSAGE National Weather Service San Francisco Bay Area 935 PM PDT Sat May 29 2021 CAZ506-507-510-511-301245- /O.CON.KMTR.HT.Y.0001.210531T1900Z-210601T0400Z/ North Bay Interior Valleys-North Bay Mountains- East Bay Interior Valleys-East Bay Hills and the Diablo Range- Including the cities of Santa Rosa, South Santa Rosa, Napa, San Rafael, Petaluma, Novato, Rohnert Park, Angwin, Lagunitas-Forest Knolls, Woodacre, Concord, Antioch, Livermore, Walnut Creek, Pleasanton, Pittsburg, San Ramon, and Blackhawk 935 PM PDT Sat May 29 2021 ...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TO 9 PM PDT MONDAY... * WHAT...Hot temperatures expected Monday. Forecast highs from the 90s to 105 F in the interior North Bay and East Bay. Overnight lows will be in the 60s and 70s in the hills, so expect little overnight relief. These will be some of our hottest temperatures of the year thus far. Sea breezes will keep daytime highs close to the ocean in the 70s, and in the 80s and lower 90s near San Francisco Bay. * WHERE...North Bay Interior Valleys, North Bay Mountains, East Bay Interior Valleys, and East Bay Hills and the Diablo Range. * WHEN...From noon to 9 PM PDT Monday. * IMPACTS...Increased risk of heat related illnesses such as heat exhaustion and heat stroke can occur due to prolonged exposure to hot temperatures. People most vulnerable include those who spend extended periods outdoors, those without air conditioning, young children, the elderly, and those with chronic illness. * ADDITIONAL DETAILS...Those seeking relief at area beaches should be mindful of cold water temperatures and dangerous rip currents. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ For more information from the National Weather Service visit http://weather.gov/mtr
788 WWUS76 KMTR 301224 NPWMTR URGENT - WEATHER MESSAGE National Weather Service San Francisco Bay Area 524 AM PDT Sun May 30 2021 CAZ506-507-510-511-302100- /O.CON.KMTR.HT.Y.0001.210531T1900Z-210601T0400Z/ North Bay Interior Valleys-North Bay Mountains- East Bay Interior Valleys-East Bay Hills and the Diablo Range- Including the cities of Santa Rosa, South Santa Rosa, Napa, San Rafael, Petaluma, Novato, Rohnert Park, Angwin, Lagunitas-Forest Knolls, Woodacre, Concord, Antioch, Livermore, Walnut Creek, Pleasanton, Pittsburg, San Ramon, and Blackhawk 524 AM PDT Sun May 30 2021 ...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TO 9 PM PDT MONDAY... * WHAT...Hot temperatures expected Monday. Forecast highs from the 90s to 105 F in the interior North Bay and East Bay. Overnight lows will be in the 60s and 70s in the hills, so expect little overnight relief. These will be some of our hottest temperatures of the year thus far. Sea breezes will keep daytime highs close to the ocean in the 70s, and in the 80s and lower 90s near San Francisco Bay * WHERE...North Bay Mountains, North Bay Interior Valleys, East Bay Interior Valleys and East Bay Hills and the Diablo Range. * WHEN...From noon to 9 PM PDT Monday. * IMPACTS...Increased risk of heat related illnesses such as heat exhaustion and heat stroke can occur due to prolonged exposure to hot temperatures. People most vulnerable include those who spend extended periods outdoors, those without air conditioning, young children, the elderly, and those with chronic illness.. * ADDITIONAL DETAILS...Those seeking relief at area beaches should be mindful of cold water temperatures and dangerous rip currents. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ For more information from the National Weather Service visit http://weather.gov/mtr
647 WWUS76 KMTR 302049 NPWMTR URGENT - WEATHER MESSAGE National Weather Service San Francisco Bay Area 149 PM PDT Sun May 30 2021 CAZ506-507-510-511-310500- /O.CON.KMTR.HT.Y.0001.210531T1900Z-210601T0400Z/ North Bay Interior Valleys-North Bay Mountains- East Bay Interior Valleys-East Bay Hills and the Diablo Range- Including the cities of Santa Rosa, South Santa Rosa, Napa, San Rafael, Petaluma, Novato, Rohnert Park, Angwin, Lagunitas-Forest Knolls, Woodacre, Concord, Antioch, Livermore, Walnut Creek, Pleasanton, Pittsburg, San Ramon, and Blackhawk 149 PM PDT Sun May 30 2021 ...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TO 9 PM PDT MONDAY... * WHAT...Hot temperatures expected Monday. Forecast highs from the 90s to 105 F in the interior North Bay and East Bay. Overnight lows will be in the 60s and 70s in the hills, so expect little overnight relief. These will be some of our hottest temperatures of the year thus far. Sea breezes will keep daytime highs close to the ocean in the 70s, and in the 80s and lower 90s near San Francisco Bay. * WHERE...North Bay Mountains, North Bay Interior Valleys, East Bay Interior Valleys and East Bay Hills and the Diablo Range. * WHEN...From noon to 9 PM PDT Monday. * IMPACTS...Increased risk of heat related illnesses such as heat exhaustion and heat stroke can occur due to prolonged exposure to hot temperatures. People most vulnerable include those who spend extended periods outdoors, those without air conditioning, young children, the elderly, and those with chronic illness. * ADDITIONAL DETAILS...Those seeking relief at area beaches should be mindful of cold water temperatures and dangerous rip currents. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ For more information from the National Weather Service visit http://weather.gov/mtr
469 WWUS76 KMTR 310448 NPWMTR URGENT - WEATHER MESSAGE National Weather Service San Francisco Bay Area 948 PM PDT Sun May 30 2021 CAZ506-507-510-511-311300- /O.CON.KMTR.HT.Y.0001.210531T1900Z-210601T0400Z/ North Bay Interior Valleys-North Bay Mountains- East Bay Interior Valleys-East Bay Hills and the Diablo Range- Including the cities of Santa Rosa, South Santa Rosa, Napa, San Rafael, Petaluma, Novato, Rohnert Park, Angwin, Lagunitas-Forest Knolls, Woodacre, Concord, Antioch, Livermore, Walnut Creek, Pleasanton, Pittsburg, San Ramon, and Blackhawk 948 PM PDT Sun May 30 2021 ...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TO 9 PM PDT MONDAY... * WHAT...Hot temperatures expected Monday. Forecast highs from the 90s to 105 F in the interior North Bay and East Bay. Overnight lows will be in the 60s and 70s in the hills, so expect little overnight relief. These will be some of our hottest temperatures of the year thus far. Sea breezes will keep daytime highs close to the ocean in the 70s, and in the 80s and lower 90s near San Francisco Bay. * WHERE...North Bay Mountains, North Bay Interior Valleys, East Bay Interior Valleys and East Bay Hills and the Diablo Range. * WHEN...From noon to 9 PM PDT Monday. * IMPACTS...Increased risk of heat related illnesses such as heat exhaustion and heat stroke can occur due to prolonged exposure to hot temperatures. People most vulnerable include those who spend extended periods outdoors, those without air conditioning, young children, the elderly, and those with chronic illness. * ADDITIONAL DETAILS...Those seeking relief at area beaches should be mindful of cold water temperatures and dangerous rip currents. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ For more information from the National Weather Service visit http://weather.gov/mtr
105 WWUS76 KMTR 311230 NPWMTR URGENT - WEATHER MESSAGE National Weather Service San Francisco Bay Area 530 AM PDT Mon May 31 2021 CAZ506-507-510-511-312100- /O.CON.KMTR.HT.Y.0001.210531T1900Z-210601T0400Z/ North Bay Interior Valleys-North Bay Mountains- East Bay Interior Valleys-East Bay Hills and the Diablo Range- Including the cities of Santa Rosa, South Santa Rosa, Napa, San Rafael, Petaluma, Novato, Rohnert Park, Angwin, Lagunitas-Forest Knolls, Woodacre, Concord, Antioch, Livermore, Walnut Creek, Pleasanton, Pittsburg, San Ramon, and Blackhawk 530 AM PDT Mon May 31 2021 ...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO 9 PM PDT THIS EVENING... * WHAT...Hot temperatures expected Monday. Forecast highs from the 90s to 105 F in the interior North Bay and East Bay. Overnight lows will be in the 60s and 70s in the hills, so expect little overnight relief. These will be some of our hottest temperatures of the year thus far. Sea breezes will keep daytime highs close to the ocean in the 70s, and in the 80s and lower 90s near San Francisco Bay. * WHERE...North Bay Mountains, North Bay Interior Valleys, East Bay Interior Valleys and East Bay Hills and the Diablo Range. * WHEN...From noon to 9 PM PDT Monday. * IMPACTS...Increased risk of heat related illnesses such as heat exhaustion and heat stroke can occur due to prolonged exposure to hot temperatures. People most vulnerable include those who spend extended periods outdoors, those without air conditioning, young children, the elderly, and those with chronic illness. * ADDITIONAL DETAILS...Those seeking relief at area beaches should be mindful of cold water temperatures and dangerous rip currents. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ For more information from the National Weather Service visit http://weather.gov/mtr
209 WWUS76 KMTR 312028 NPWMTR URGENT - WEATHER MESSAGE National Weather Service San Francisco Bay Area 128 PM PDT Mon May 31 2021 CAZ506-507-510-511-010400- /O.CON.KMTR.HT.Y.0001.000000T0000Z-210601T0400Z/ North Bay Interior Valleys-North Bay Mountains- East Bay Interior Valleys-East Bay Hills and the Diablo Range- Including the cities of Santa Rosa, South Santa Rosa, Napa, San Rafael, Petaluma, Novato, Rohnert Park, Angwin, Lagunitas-Forest Knolls, Woodacre, Concord, Antioch, Livermore, Walnut Creek, Pleasanton, Pittsburg, San Ramon, and Blackhawk 128 PM PDT Mon May 31 2021 ...HEAT ADVISORY REMAINS IN EFFECT UNTIL 9 PM PDT THIS EVENING... * WHAT...Forecast highs from the 90s to 105 F in the interior North Bay and East Bay. Overnight lows will be in the 60s and 70s in the hills, so expect little overnight relief. These will be some of our hottest temperatures of the year thus far. * WHERE...North Bay Mountains, North Bay Interior Valleys, East Bay Interior Valleys and East Bay Hills and the Diablo Range. * WHEN...Until 9 PM PDT Monday. * IMPACTS...Increased risk of heat related illnesses such as heat exhaustion and heat stroke can occur due to prolonged exposure to hot temperatures. People most vulnerable include those who spend extended periods outdoors, those without air conditioning, young children, the elderly, and those with chronic illness. * ADDITIONAL DETAILS...Those seeking relief at area beaches should be mindful of cold water temperatures and dangerous rip currents. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ For more information from the National Weather Service visit http://weather.gov/mtr
283 WWUS76 KMTR 010352 NPWMTR URGENT - WEATHER MESSAGE National Weather Service San Francisco Bay Area 852 PM PDT Mon May 31 2021 CAZ506-507-510-511-010500- /O.EXP.KMTR.HT.Y.0001.000000T0000Z-210601T0400Z/ North Bay Interior Valleys-North Bay Mountains- East Bay Interior Valleys-East Bay Hills and the Diablo Range- Including the cities of Santa Rosa, South Santa Rosa, Napa, San Rafael, Petaluma, Novato, Rohnert Park, Angwin, Lagunitas-Forest Knolls, Woodacre, Concord, Antioch, Livermore, Walnut Creek, Pleasanton, Pittsburg, San Ramon, and Blackhawk 852 PM PDT Mon May 31 2021 ...HEAT ADVISORY WILL EXPIRE AT 9 PM PDT THIS EVENING... Peak heating from earlier today is winding down so the Heat Advisory will be allowed to expire. $$ For more information from the National Weather Service visit http://weather.gov/mtr
What forecasters said that day
The local office's own words before this heat advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS San Francisco Bay Area, CA wrote its last area forecast discussion before this heat advisory went out at May 28, 11:19 AM PDT, 1 hour 22 minutes earlier.
Area forecast discussion, May 28, 11:19 AM PDT, 1 hour 22 minutes before
Area Forecast Discussion
National Weather Service San Francisco Bay Area
1119 AM PDT Fri May 28 2021
.SYNOPSIS...Temperatures will remain near seasonal averages from
Friday into Saturday with periods of night and morning low clouds
near the coast. A robust warming trend is then forecast to begin
across the interior Sunday before peaking on Memorial Day as high
pressure strengthens across the region.
.DISCUSSION...as of 08:52 AM PDT Friday...GOES-WEST True-Color
imagery showing some light ripples along the marine stratus deck
due west of Monterey Bay this morning. Stratus is quickly mixing
out along the Bay Shoreline and will gradually make way for
clearer skies in the interior this afternoon, with some of it
lingering along portions of the coast. Temps at and above the East
Bay foothills, North Bay Mountains, Santa Cruz Mountains, and the
Santa Lucia Range are already running 5-10 F warmer than this
time 24 hours ago, consistent with the robust warming trend that
will begin today and carry into the weekend.
&&
.PREV DISCUSSION...as of 03:11 AM PDT Friday...Satellite imagery at
this hour is showing a bit more widespread coastal stratus this
morning spreading inland into the East Bay and down into the
Salinas Valley. Additionally, temperatures are running a few to
several degrees warmer compared to 24 hours ago as the mid/upper
level trough that pushed inland into the Pacific Northwest shifts
further inland. As a result, look for temperatures across the
interior to be slightly warmer this Friday afternoon while some
coastal locations may cool a degree or two in response to
increased cloud cover and onshore winds. Only minor changes are
anticipated for Saturday with coastal temperatures ranging from
the upper 50s to mid 60s while 70s to mid 80s continue inland.
Breezy afternoon and evening winds are also expected to impact the
region through Saturday.
A robust warming trend is then forecast to get underway on Sunday as
mid/upper level high pressure over the eastern Pacific nudges inland
over the Pacific Northwest and northern California. This will allow
for offshore flow to develop over the higher terrain of the greater
San Francisco Bay Area as temperatures aloft also begin to warm. The
offshore flow won't be overly strong, but enough to usher in much
drier air, gusty winds and mix down warmer temperatures to the
surface. Thus, more widespread 90s are likely across the interior
with places such as Lake Berryessa potentially reaching the 100 deg
F mark. Meanwhile, onshore flow is forecast to persist near the coast
and around the bays holding temperatures in the 60s (west/northwest
facing areas), 70s for places such as Santa Cruz and into the
low/mid 80s around the San Francisco Bay shoreline. The
aforementioned dry air mass and offshore flow in the hills, ridges
and peaks will keep overnight temperatures mild, likely in the 60s
to lower 70s while coastal and valley locations see more adequate
cooling.
Forecast ensembles indicate the ridge will strengthen aloft on
Memorial Day with near record 850 mb temperatures across the Bay
Area for late May. In turn, look for more widespread mid/upper 90s
across inland areas with the potential for 100-104 deg F afternoon
temperatures in the region's warmest interior spots. Meanwhile, all
guidance at this point continues to suggest the region's natural
air conditioning (cool sea surface temperatures across the Pacific
and onshore flow) will remain in service near the coast. Thus, look
for mid 60s to upper 70s near the coast while areas around the San
Francisco Bay Shoreline and inland from the Monterey Bay warm into
the 80s to lower 90s. At this time, the Heat Risk looks to reach
moderate to high (daytime alone across the interior) with adequate
overnight cooling helping to limit higher risk levels overall from
Sunday night through Monday night. That said, folks sensitive to
heat should be vigilant about staying cool and hydrated during the
hottest part of the day. Additionally, beachgoers should remain
cautious during the Memorial Day Holiday as ocean temperatures
remain in the low/mid 50s which increases the risk of cold water
shock and drowning should one inadvertently fall or be pulled into
the ocean. Lastly, while widespread critical fire weather conditions
are not anticipated, hot and dry weather along with very dry fuels
will pose an elevated fire threat. With approximately 95% of all
wildfires across the state being caused by human activity, please
avoid any actives that could create an accidental fire start.
While temperatures begin to cool slightly region-wide on Tuesday,
above average temperatures will persist across the interior into
mid/late week. Coastal locations will be the first to see cooling as
onshore flow increases and the weak offshore flow over the interior
diminishes. Should also see a return of night/morning stratus near
the coast and breezy afternoon seabreezes by late week.
&&
.AVIATION...as of 4:57 AM PDT Friday...For the 18z TAFs. Thinning
cloud cover will lead to VFR into the afternoon but stratus looks
to linger along the immediate coast. The afternoon will allow for
breezy westerly winds which will last into the evening. Coastal
stratus will begin to move inland in the evening, leading to IFR
around the Monterey Bay. IFR will affect more terminals overnight
with North Bay and Monterey Bay locations seeing the LIFR as cigs
fall below 500 ft AGL.
Vicinity of KSFO...VFR for the afternoon with gusty winds. Expect winds from
the west around 17 kts and around 27 kt gusts. Expect IFR in the
late night as CIGs fall below 1000 ft AGL. Cloud cover lifts to MVFR
mid morning Saturday, and thins for VFR that afternoon with more
gusty westerly winds.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...MVFR turns to VFR into the afternoon as
cloud cover thins. Expect breezy westerly winds through the
afternoon and lingering into the evening. IFR returns in the early
evening as low stratus moves inland from the coast. CIGS fall
further into the night calling for LIFR as ceilings fall below 500
ft AGL until mid morning Saturday.
&&
.MARINE...as of 11:16 AM PDT Friday...High pressure along the West
Coast and low pressure inland will maintain gusty northwest winds
over the waters. These stronger winds will result in wind driven
seas with smaller southerly and northwesterly swells. Coastal
jets will develop in between Point Arena and Point Reyes, as well
as along the Big Sur Coast south of Point Sur in the afternoon and
evening hours. The gusty winds will produce hazardous conditions
to smaller vessels.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pt Reyes to Pigeon Pt 0-10 nm
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
SCA...SF Bay from 3 PM
SCA...Mry Bay from 3 PM
&&
PUBLIC FORECAST: Diaz/RGass
AVIATION: Murdock
MARINE: Canepa
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www.youtube.com/nwsbayareaThe office that day
Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 28, 3:34 AM PDT | Small Craft Advisory | MTR | 71 hr |
Nearby
Heat Advisories in California, 2021Every heat advisory in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.