Alert archive / California / Excessive Heat Warnings in 2021
Excessive Heat Warning 1, NWS San Diego, CA
NWS San Diego, CA issued this excessive heat warning at Jun 1, 2021, 2:08 PM PDT for Riverside County, San Bernardino County, San Diego County, California. It took effect at Jun 2, 2021, 11:00 AM PDT. It was in force for 58 hr. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Jun 1, 2021, 2:08 PM PDT (21:08 UTC)
- In effect from
- Jun 2, 2021, 11:00 AM PDT
- Expired
- Jun 4, 2021, 9:00 PM PDT
- In force
- 58 hr
- Issued by
- NWS San Diego, CA
Counties Riverside County, CA, San Bernardino County, CA, San Diego County, CA
The radar
The Santa Ana Mts radar (KSOX), 122 km from the middle of the area, began a volume at 21:14 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
San Diego, CA (KNKX), launched 12:00Z, 9.1 hours before the alert went out and 145 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1164 m above ground
- 0-6 km bulk shear
- 22 kt
- 0-1 km storm-relative helicity
- 18 m²/s²
- 0-3 km storm-relative helicity
- 49 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
173 WWUS76 KSGX 012108 NPWSGX URGENT - WEATHER MESSAGE National Weather Service SAN DIEGO CA 208 PM PDT Tue Jun 1 2021 CAZ060-021100- /O.NEW.KSGX.EH.W.0001.210602T1800Z-210604T0300Z/ Apple and Lucerne Valleys- Including the cities of Victorville, Hesperia, and Apple Valley 208 PM PDT Tue Jun 1 2021 ...EXCESSIVE HEAT WARNING IN EFFECT FROM 11 AM WEDNESDAY TO 8 PM PDT THURSDAY... * WHAT...Dangerously hot conditions with afternoon high temperatures of 98 to 103 degrees expected. * WHERE...Apple and Lucerne Valleys. * WHEN...From 11 AM Wednesday to 8 PM PDT Thursday. * IMPACTS...Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. 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. && $$ CAZ061-062-021100- /O.NEW.KSGX.EH.W.0001.210602T1800Z-210605T0400Z/ Coachella Valley-San Diego County Deserts- Including the cities of Indio, Palm Springs, Cathedral City, Palm Desert, Palm Desert Country, La Quinta, Coachella, and Borrego Springs 208 PM PDT Tue Jun 1 2021 ...EXCESSIVE HEAT WARNING IN EFFECT FROM 11 AM WEDNESDAY TO 9 PM PDT FRIDAY... * WHAT...Dangerously hot conditions. Afternoon high temperatures of 105 to 110 degrees are expected each day. Overnight lows will only cool to the mid to upper 70s most areas. * WHERE...Coachella Valley and San Diego County Deserts. * WHEN...From 11 AM Wednesday to 9 PM PDT Friday. * IMPACTS...Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ For more information from the National Weather Service visit http://weather.gov/sandiego
8 follow-up statements
950 WWUS76 KSGX 021002 NPWSGX URGENT - WEATHER MESSAGE National Weather Service SAN DIEGO CA 302 AM PDT Wed Jun 2 2021 CAZ060-022230- /O.CON.KSGX.EH.W.0001.210602T1800Z-210604T0300Z/ Apple and Lucerne Valleys- Including the cities of Victorville, Hesperia, and Apple Valley 302 AM PDT Wed Jun 2 2021 ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT FROM 11 AM THIS MORNING TO 8 PM PDT THURSDAY... * WHAT...Dangerously hot conditions with temperatures up to 102 expected. * WHERE...Apple and Lucerne Valleys. * WHEN...From 11 AM this morning to 8 PM PDT Thursday. * IMPACTS...Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. 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. && $$ CAZ061-062-022230- /O.CON.KSGX.EH.W.0001.210602T1800Z-210605T0400Z/ Coachella Valley-San Diego County Deserts- Including the cities of Indio, Palm Springs, Cathedral City, Palm Desert, Palm Desert Country, La Quinta, Coachella, and Borrego Springs 302 AM PDT Wed Jun 2 2021 ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT FROM 11 AM THIS MORNING TO 9 PM PDT FRIDAY... * WHAT...Dangerously hot conditions with temperatures up to 110 expected. * WHERE...San Diego County Deserts and Coachella Valley. * WHEN...From 11 AM this morning to 9 PM PDT Friday. * IMPACTS...Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ For more information from the National Weather Service visit http://weather.gov/sandiego 17
443 WWUS76 KSGX 022034 NPWSGX URGENT - WEATHER MESSAGE National Weather Service SAN DIEGO CA 134 PM PDT Wed Jun 2 2021 CAZ060-030500- /O.CON.KSGX.EH.W.0001.000000T0000Z-210604T0300Z/ Apple and Lucerne Valleys- Including the cities of Victorville, Hesperia, and Apple Valley 134 PM PDT Wed Jun 2 2021 ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM PDT THURSDAY... * WHAT...Dangerously hot conditions with temperatures up to 103 expected. * WHERE...Apple and Lucerne Valleys. * WHEN...Through 8 PM PDT Thursday. * IMPACTS...Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. 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. && $$ CAZ061-062-030500- /O.CON.KSGX.EH.W.0001.000000T0000Z-210605T0400Z/ Coachella Valley-San Diego County Deserts- Including the cities of Indio, Palm Springs, Cathedral City, Palm Desert, Palm Desert Country, La Quinta, Coachella, and Borrego Springs 134 PM PDT Wed Jun 2 2021 ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 9 PM PDT FRIDAY... * WHAT...Dangerously hot conditions with temperatures of 105 to 110 expected. * WHERE...San Diego County Deserts and Coachella Valley. * WHEN...Through 9 PM PDT Friday. * IMPACTS...Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ SS For more information from the National Weather Service visit http://weather.gov/sandiego
242 WWUS76 KSGX 030438 NPWSGX URGENT - WEATHER MESSAGE National Weather Service SAN DIEGO CA 938 PM PDT Wed Jun 2 2021 CAZ060-031245- /O.CON.KSGX.EH.W.0001.000000T0000Z-210604T0300Z/ Apple and Lucerne Valleys- Including the cities of Victorville, Hesperia, and Apple Valley 938 PM PDT Wed Jun 2 2021 ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM PDT THURSDAY... * WHAT...Dangerously hot conditions with temperatures up to 103 expected. * WHERE...Apple and Lucerne Valleys. * WHEN...Through 8 PM PDT Thursday. * IMPACTS...Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. 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. && $$ CAZ061-062-031245- /O.CON.KSGX.EH.W.0001.000000T0000Z-210605T0400Z/ Coachella Valley-San Diego County Deserts- Including the cities of Indio, Palm Springs, Cathedral City, Palm Desert, Palm Desert Country, La Quinta, Coachella, and Borrego Springs 938 PM PDT Wed Jun 2 2021 ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 9 PM PDT FRIDAY... * WHAT...Dangerously hot conditions with temperatures of 105 to 110 expected. * WHERE...San Diego County Deserts and Coachella Valley. * WHEN...Through 9 PM PDT Friday. * IMPACTS...Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ For more information from the National Weather Service visit http://weather.gov/sandiego jmb
225 WWUS76 KSGX 031051 NPWSGX URGENT - WEATHER MESSAGE National Weather Service SAN DIEGO CA 351 AM PDT Thu Jun 3 2021 CAZ060-032230- /O.CON.KSGX.EH.W.0001.000000T0000Z-210604T0300Z/ Apple and Lucerne Valleys- Including the cities of Victorville, Hesperia, and Apple Valley 351 AM PDT Thu Jun 3 2021 ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM PDT THIS EVENING... * WHAT...Dangerously hot conditions with temperatures up to 102. * WHERE...Apple and Lucerne Valleys. * WHEN...Until 8 PM PDT this evening. * IMPACTS...Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. 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. && $$ CAZ061-062-032230- /O.CON.KSGX.EH.W.0001.000000T0000Z-210605T0400Z/ Coachella Valley-San Diego County Deserts- Including the cities of Indio, Palm Springs, Cathedral City, Palm Desert, Palm Desert Country, La Quinta, Coachella, and Borrego Springs 351 AM PDT Thu Jun 3 2021 ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 9 PM PDT FRIDAY... * WHAT...Dangerously hot conditions with temperatures up to 106. * WHERE...San Diego County Deserts and Coachella Valley. * WHEN...Until 9 PM PDT Friday. * IMPACTS...Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ For more information from the National Weather Service visit http://weather.gov/sandiego 17
673 WWUS76 KSGX 032031 NPWSGX URGENT - WEATHER MESSAGE National Weather Service SAN DIEGO CA 131 PM PDT Thu Jun 3 2021 CAZ060-040300- /O.CON.KSGX.EH.W.0001.000000T0000Z-210604T0300Z/ Apple and Lucerne Valleys- Including the cities of Victorville, Hesperia, and Apple Valley 131 PM PDT Thu Jun 3 2021 ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM PDT THIS EVENING... * WHAT...Dangerously hot conditions with temperatures up to 102. * WHERE...Apple and Lucerne Valleys. * WHEN...Until 8 PM PDT this evening. * IMPACTS...Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. 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. && $$ CAZ061-062-040445- /O.CON.KSGX.EH.W.0001.000000T0000Z-210605T0400Z/ Coachella Valley-San Diego County Deserts- Including the cities of Indio, Palm Springs, Cathedral City, Palm Desert, Palm Desert Country, La Quinta, Coachella, and Borrego Springs 131 PM PDT Thu Jun 3 2021 ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 9 PM PDT FRIDAY... * WHAT...Dangerously hot conditions with temperatures up to 108. * WHERE...San Diego County Deserts and Coachella Valley. * WHEN...Until 9 PM PDT Friday. * IMPACTS...Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. && $$ Maxwell
973 WWUS76 KSGX 040347 NPWSGX URGENT - WEATHER MESSAGE National Weather Service SAN DIEGO CA 847 PM PDT Thu Jun 3 2021 CAZ061-062-041300- /O.CON.KSGX.EH.W.0001.000000T0000Z-210605T0400Z/ Coachella Valley-San Diego County Deserts- Including the cities of Indio, Palm Springs, Cathedral City, Palm Desert, Palm Desert Country, La Quinta, Coachella, and Borrego Springs 847 PM PDT Thu Jun 3 2021 ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 9 PM PDT FRIDAY... * WHAT...Dangerously hot conditions with temperatures up to 108. * WHERE...San Diego County Deserts and Coachella Valley. * WHEN...Until 9 PM PDT Friday. * IMPACTS...Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. 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. && $$ For more information from the National Weather Service visit http://weather.gov/sandiego jmb
729 WWUS76 KSGX 041228 NPWSGX URGENT - WEATHER MESSAGE National Weather Service SAN DIEGO CA 528 AM PDT Fri Jun 4 2021 CAZ061-062-050400- /O.CON.KSGX.EH.W.0001.000000T0000Z-210605T0400Z/ Coachella Valley-San Diego County Deserts- Including the cities of Indio, Palm Springs, Cathedral City, Palm Desert, Palm Desert Country, La Quinta, Coachella, and Borrego Springs 528 AM PDT Fri Jun 4 2021 ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 9 PM THIS EVENING... * WHAT...Dangerously hot conditions with temperatures up to 108. * WHERE...San Diego County Deserts and Coachella Valley. * WHEN...Until 9 PM today. * IMPACTS...Increased potential for heat related illnesses, particularly for those working or participating in outdoor activities. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. && $$ Moede
555 WWUS76 KSGX 042222 NPWSGX URGENT - WEATHER MESSAGE National Weather Service SAN DIEGO CA 322 PM PDT Fri Jun 4 2021 CAZ061-062-050400- /O.CON.KSGX.EH.W.0001.000000T0000Z-210605T0400Z/ Coachella Valley-San Diego County Deserts- Including the cities of Indio, Palm Springs, Cathedral City, Palm Desert, Palm Desert Country, La Quinta, Coachella, and Borrego Springs 322 PM PDT Fri Jun 4 2021 ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 9 PM PDT THIS EVENING... * WHAT...Dangerously hot conditions with temperatures up to 108. * WHERE...San Diego County Deserts and Coachella Valley. * WHEN...Until 9 PM today. * IMPACTS...Increased potential for heat related illnesses, particularly for those working or participating in outdoor activities. 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/sandiego jmb
What forecasters said that day
The local office's own words before this excessive heat warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS San Diego, CA wrote its last area forecast discussion before this excessive heat warning went out at Jun 1, 9:42 AM PDT, 4 hours 26 minutes earlier.
Area forecast discussion, Jun 1, 9:42 AM PDT, 4 hours 26 minutes before
Area Forecast Discussion National Weather Service San Diego CA 942 AM PDT Tue Jun 1 2021 .SYNOPSIS... High pressure to the north and low pressure to the south will move slowly toward the south and east through Friday. Slow warming will continue into Thursday. Mid level moisture in the easterly flow aloft will bring some afternoon clouds to the mountains through Wednesday. The marine layer will become gradually shallower into Friday morning with night and morning coastal low clouds not spreading as far into the valleys. Slow and limited daytime clearing will continue near the coast. Cooling will spread inland for the weekend through early next week with coastal low clouds spreading farther into the valleys. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Marine layer stratus is burning off quickly this morning, already confined to only the immediate coast as of 1630Z. This is despite the inversion being a little stronger on this morning's 12Z sounding. Will see at least some periods of clearing for the beaches and immediate coast this afternoon before low clouds begin spreading inland again very late afternoon. Upper ridging was centered across northern California this morning with an upper low across the northern Baja. The warming trend will continue today with readings expected to climb to 5 to 8 degrees warmer than yesterday for much of the valleys/deserts. The upper ridge will continue to shift southward will be centered over central California Wednesday through Friday, which will be the warmest days for the southern California valleys/deserts. Will take a close look at the max temp forecast this period for the afternoon forecast update. Some mid level moisture is wrapping around the upper low to our south. PWs of 0.8-0.9 inch are expected across the mountains the next couple of afternoons. For the most part just a few CBs are expected to form. There remains a very slight chance of an isolated shower or stray lightning strike forming over the mountains this afternoon/Wednesday afternoon. POPs are at 10 percent or less and there will be no mention of precip in the forecast. Previous Discussion (Issued 443 AM PDT Tue Jun 1 2021)... SHORT TERM (Today through Thursday)... High pressure to the north and low pressure to the south will move slowly toward the south and east through Friday. The change from recent forecasts is the high moves farther south in response to an upstream low pressure system moving across the eastern Pacific. The gradual warming trend will continue into Thursday. With the warming, high temperatures on Thursday will be a few degrees above average for coastal areas into the San Diego County valleys and 5 to 10 degrees above average farther inland with high temperatures around 108 in the lower deserts, around 100 in the high desert, and in the lower to mid 90s in the Inland Empire. The marine layer will become a little shallower with the night and morning low clouds and fog not spreading as far inland into the valleys. Daytime clearing near many beaches will continue to be slow and limited as May Gray makes a smooth hand-off to June Gloom. Mid level moisture in easterly flow aloft between high pressure to the north and low pressure to the south will continue to bring some afternoon clouds to the mountains for today and Wednesday. Chances are small, less than 10 percent, for isolated showers in the mountains with light rainfall and gusty winds. Chances for isolated thunderstorms with dry lightning and gusty winds are even less. LONG TERM (Friday through Monday)... High pressure aloft will continue to slowly decrease the depth of the marine layer into Friday morning with coastal low clouds spreading into the western valleys for Thursday night into Friday morning. The latest deterministic runs of the global models have a weak trough of low pressure off the California coast early Friday developing into a weak closed upper low and drifting southward on Saturday, then moving eastward and inland across southern California and northern Baja some time around late Sunday through Monday as another trough of low pressure moves across the eastern Pacific toward the West Coast. It's not clear how much continuity this feature will have in later model forecasts. Such a weak upper low, should it materialize, could bring some light precipitation as it moves inland. However, there remains no rain in the forecast. It is not until the 90th percentile of precipitation chances of the ECMWF ensemble members until chances for measurable precipitation exceed 10 percent. Regardless of the specifics, onshore flow should begin to strengthen on Friday with slight cooling on Friday and greater cooling spreading inland for the weekend into early next week. The marine layer should deepen with night and morning coastal low clouds and fog spreading farther into the inland valleys. For late in the weekend into early next week, the model uncertainly along the West Coast is centered primarily on the amplitude of the trough of low pressure nearing the West Coast and to a lesser extent on the timing of that system. Those solutions that are more zonal and weaker with this system would have less cooling for southern California and not as much deepening of the marine layer. Those solutions with greater amplitude to the trough and movement taking it closer to the coast would have greater cooling and deepening of the marine layer for southern California. High temperatures for early next week would be at least a few degrees below average. && .AVIATION... 011630Z...Coast/Valleys...Low clouds with bases 1200-1600 ft MSL and tops to 2000 ft MSL will clear to near the coast by 18Z, but locations within 3 miles of the coast will have intermittent BKN-OVC cloud cover this afternoon. SAN/CRQ will have some SCT conditions today but could return to a BKN CIG after 22Z. Stratus will spread back inland tonight, up to 25 miles from the coast, with bases a little lower at 1000-1300 ft MSL and tops to 1700 ft MSL. Local vis 1-3 miles will occur in the valleys 08Z-16Z Wed. Areas of higher terrain will be obscured at times again overnight into Wed morning. Most areas will clear 16Z-19Z Wed. Otherwise...Mostly clear skies and unrestricted vis will prevail through Wed morning, except for areas of cumulus over the mountains between 19Z and 01Z with bases around 10000 feet MSL. && .MARINE... No hazardous marine conditions are expected through Saturday. && .BEACHES... A couple of long-period south swells will bring elevated surf to south-faces beaching Wed-Sun, especially in Orange County. Surf will mostly be 3-5 feet with local sets to 6 feet possible. This will be accompanied by a high risk of rip currents. && .FIRE WEATHER... High pressure to the north and low pressure to the south will maintain easterly flow over southern California California into the Wednesday. This will transport small amounts of mid and high level moisture into southern California with some afternoon clouds over the mountains. Chances are small, less than 10 percent, for isolated showers in the mountains with light rainfall and gusty winds. Chances for isolated thunderstorms with dry lightning and gusty winds are even less. This pattern will drift southward on Thursday decreasing the flow of mid level moisture and stabilizing the atmosphere as high pressure moves over southern California. Strong onshore flow for late in the week into the weekend will bring stronger and gusty southwest to west winds in the mountains and deserts, developing in the afternoon and continuing through the evening each day. These winds, combined with lowest daytime humidity of 10 to 15 percent, will bring elevated fire weather conditions to the deserts each afternoon for Thursday through Saturday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && PUBLIC...Moreland AVIATION/MARINE...Maxwell
Nearby
Excessive Heat Warnings in California, 2021Every excessive heat warning 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.