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Hot, Dry Conditions Prompt Red Flag Warning In San Diego

The San Diego Fire-Rescue Department Station 1 is shown in this undated photo.
Milan Kovacevic
The San Diego Fire-Rescue Department Station 1 is shown in this undated photo.
Hot, Dry Conditions Prompt Red Flag Warning In San Diego
Hot, Dry Conditions Prompt Red Flag Warning In San Diego GUEST: Alex Tardy, warning coordination meteorologist, National Weather Service

This is KPBS Midday Edition. I'm Maureen Cavanaugh it is Monday, October 23. Our top story on midday edition it's one of those fall days in San Diego where many of us will watch the sky and sniff the air. Red flag warning is in effect indicating increased fire danger as a very hot dry winds move in. 85 schools in the San Diego unified district will have half days today. Schools in Coronado are closed. Joining me is Alex Tardy, warning coordination meteorologist, National Weather Service. How hot is it expected to get?The hottest days will be today and tomorrow. I think most locations will see their highest temperature on Tuesday. I think all areas are going to be over 100. The only exception would be maybe Downtown San Diego or La Jolla, Oceanside right on the beach where it will be mid to upper 90s. Some extreme locations like a long Interstate 15, a Mesa, that area will top out around 105 maybe 107. I did not want to say low 100s because that is vague 105 and 107 in the hottest spots.What about humidity?This is the event that the wind is star by moisture. A pushes out the Marine layer and our natural cooling that we get. Humidity is very low. Skin is dry in sinuses. What makes us so unusual is not that were having the Santa Ana winds it's the fact that the air mass not coming from the desert but above us is so potentially warm that we will see record-breaking temperatures and those 105 two 106 readings. We have the worst case scenario. We have the wind and the big dome of high pressure.I saw mention of the Santa Ana wildfire threat index. What is that?The U.S. for service has done a lot of research with us and also with San Diego gas and electric. It is the index that tells the public and to tell partners such as Cal fire that the danger and red flag warnings are not always the same. Some red flag warnings you don't have as much danger and others you have considerable danger. It tries to rank it based on historical wildfires. So it puts all the weather element combined with given those weather elements have you had big wildfires? In this case, it's putting us in the moderate category, which indicates we've had big fires in these situations.You mentioned this is not unusual weather for us at this time of year. We had sprinkles in light rain on Friday. What caused this dramatic turnaround?It happens quick. Typically what brings it in our region is a storm system going way to the north across Salt Lake City. They had a dust storm last week from the vicious cold front that moved through. That in turn is what flushes out all of the cool, moist air. It could happen in 24 to 36 hours where you go from damp, cool conditions to perfectly clear visibility. That is the sign right there.So since this is fall and not summertime, we should get relief from the heat during the evening, is that right?We of longer days, of course. The key will be that the air is dry . We will cool off at night. The hotter we get in the day it's going to take a while to feel cool. People will be using their air-conditioning even at night despite the fact that overnight we will see temperatures drop into the 60s and lower 70s.Because your house is going to trap so much eat.Yes, your house is sitting out there in the hot sun and it is absorbing all that heat and he gets captured into the materials of the house and also into the attic. Unless you flush it out, the air condition is going to fight against that.What about the winds?The night time when you have these Santa Ana conditions not everybody sees winds. What happens at night is when the wind keeps blowing, it asked to keep us hotter. Keeps the air mix. When the sun comes out in the middle the day or during the day, it heats the ground and that causes hot air currents to rise. The wind can do the same thing. While the wind cannot keep over hundred it can keep some places in the 80s. Places that stay breezy the next two nights are going to be ridiculously warm. Places that cool off will be because they lose all that went in all the hot air escapes. That went can act like the sun at nighttime.Warm weather is expected to peak tomorrow and last until Wednesday. What can we expect after that question markIt's going to be a slow transition. First our beaches and then immediate coast when the Santa Ana pulls away, we will see fog forming and cooler conditions. For as inland like a long Interstate 15, it's going to be a very slow cool down. Instead of seeing 105 on Tuesday, will drop down close to 100. The long-range Outlook does not keep us anywhere near below normal. If you're looking for below normal temperatures , we don't see it in the future . We will stay above normal but this heatwave the next two days is going to be excessively hot in terms of temperatures.I been speaking with Alex Tardy, warning coordination meteorologist, National Weather Service. Thank you.Thank you.

Santa Ana winds will rake much of San Diego County Monday and combine with record-high temperatures and extremely dry air to create dangerous fire conditions, forecasters said.

The extreme heat, expected to be 20 to 25 degrees above seasonal averages Monday, has prompted schools across San Diego to implement minimum-day schedules, while fire agencies across the county have beefed up staffing to deal with potentially dangerous wildfires.

A Red Flag Fire Warning issued by the National Weather Service for parts of San Diego County was scheduled to be in effect until 6 p.m. Wednesday amid forecasts of hot, dry and windy weather in the inland valleys and mountains. The combination of extreme heat, low humidity and Santa Ana winds will create an increased threat of wildfire ignition and large fire growth, the NWS said.

The U.S. Forest Service warned that wildfires that ignite Monday in San Diego County "may grow rapidly." The Santa Ana Wildfire Threat Index will be increased Tuesday, when any fire that ignites "will grow rapidly and will be difficult to control."

RELATED: San Diego Red Flag Warning Prompts Cal Fire Staffing Levels Boost

To prepare for the increased danger of rapidly-spreading wildfires, Cal Fire, the San Diego Fire-Rescue Department and the Cleveland National Forest have all beefed up firefighting staffing levels.

Two sizeable fires erupted over the weekend. The "Church Fire" in Campo scorched about 100 acres Saturday and was expected to be fully contained Monday. The "El Capitan Fire," sparked Saturday afternoon by a plane crash that authorities believe killed two people, burned about 20 acres before firefighters brought the flames under control Saturday night.

Originally set to end Tuesday evening, the Red Flag warning was extended to 6 p.m. Wednesday as models showed high winds were expected to continue for an additional day, the NWS said. Forecasters expect Santa Ana winds to strengthen throughout Monday with gusts reaching up to 60 mph in certain spots. Meanwhile, humidity was expected to drop to about 5 percent Monday and Tuesday.

The high in the city of San Diego Monday was forecast at 93 degrees, which would match the previous record high for the date set in 1965. If Vista hits its expected high of 102, it will break the previous record high of 99 set in 1965. El Cajon is expected to touch 100 to match the previous record high set in 2003, while Ramona's forecast of 99 would break its previous record high for the date, also set in 2003. If Alpine hits its forecast high of 99 Monday, it will break the previous Oct. 23 record of 98 set in 1959.

With such extreme seasonal heat in the forecast, 85 schools in the San Diego Unified School District have announced minimum-day schedules Monday, including Morse, Mission Bay and La Jolla high schools.

The Red Flag warning that went into effect Sunday came on the 10th anniversary of the start of the October 2007 wildfires that wrought havoc on the San Diego region. Wednesday will mark the 14th anniversary of the deadly and destructive Cedar Fire of 2003.