INTRODUCTION TO METEOROLOGY PART THREE SC 212 JUNE 2, 2015 JOHN BUSH

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2 INTRODUCTION TO METEOROLOGY PART THREE SC 212 JUNE 2, 2015 JOHN BUSH

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4 Lecture 24 The Imperfect Forecast The 2015 Snowstorm of the Century (that wasn t) Features of California weather Meteorology-related research at UCI

5 THE IMPERFECT FORECAST DVD

6 THE BLIZZARD OF 2015 US ADMITS FORECAST ERROR US model gave two predictions of the track US meteorologists had to decide on one They chose the one close to the European model prediction They were wrong by about 100 miles New Jersey and New York City shut down based on the Weather Service prediction

7 EUROPE VERSUS AMERICA 2012 Hurricane Sandy: US Global Forecast System (GFS) failed badly while Europeans System prediction was correct Congress appropriated $34 million to fix the GFS- finer grid and (eventually) a faster computer European system still beats US in predicting height of the 500 mb surface a standard test

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9 CALIFORNIA WEATHER Precipitation: Rain, Drizzle, Snow, Sleet/Graupel, Hail, Dew, Frost Extra tropical cyclones Hurricanes (Tropical Storms) Summer monsoons Atmospheric rivers Marine layer condensation Winds Winter storms Hurricanes Tornadoes, waterspouts Dust devils, waterspouts, fire devils Orographic winds Sea breeze fronts

10 MORE CALIFORNIA WEATHER Clouds May Gray/June Gloom Visibility Marine fog Tule fog Sea haze Smog Lighting Refraction, reflection, scattering phenomena Earthquake lights Wildfires

11 PRECIPITATION-ETCs NW->SE tracking storms Originate over Western Siberia/Aleutian Low Steered by jet-streams, influenced by Rossby waves North Pacific High in winter is smaller and located to the southeast In summer the High moves toward Hawaii and increases in area

12 WINTER LOCATIONS

13 SUMMER LOCATIONS

14 SUMMER MONSOONS Centered in Northern Mexico June- September Provide episodic California rainfall in the Central Valley south to Mexican Border Created by thermal lows, steered by high pressure ridge aloft Moisture is drawn from Sea of Cortez, eastern Pacific and Gulf of Mexico

15 MONSOON CLOUDS EL CAJON CALIFORNIA

16 HURRICANES Generally occur in August and September Degrade to tropical storms or depressions before landfall Average 1 rainfall-producer every 3 years Occasionally cause serious flooding September 1932 S. California 4 days of rain 15 people killed September 1939 Long Beach landfall 45 killed September 1976 Ocotilla flood 3 killed

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18 ATMOSPHERIC RIVERS (ARs) Formed in the Western Pacific Madden-Julian Oscillation ENSO Steered by a southern branch of the polar jet stream Can produce extended periods of heavy rainfall-can channel a greater moisture flow than the Amazon

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20 2010 ATMOSPHERIC RIVER

21 WATER VAPOR IMAGE

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23 SOME AR EVENTS Great Storm of Recent January December December ARkStorm

24 ARkStorm

25 WINDS Sea breeze fronts Winter storms Hurricanes Tornadoes Dust devils, waterspouts, fire devils Orographic winds

26 TORNADOES Since 1950 there have been about 10/yr Some Statistics Intensity: EF3 2, EF2 23, EF1 91 Injuries 85, deaths 0 County tornado count/1000 mi 2 : Orange 39, Sacramento 11, Los Angeles 11, San Diego 6 Includes tornadic water spouts that come onto shore

27 WATER SPOUTS Fair weather waterspouts Formed by convective action under developing cumulus clouds Wind speed < 30m/s, Life < 20min,Intensity <EF0 Tornadic waterspouts Formed by severe thunderstorms over water or by land tornadoes travelling over water Intensity> EF1 maximum unspecified

28 DUST DEVILS Formed by buoyant hot air near the ground and some vorticity source such as wind shear Dies when converging cooler air eliminates the buoyancy from seconds to <20 minutes Top wind speeds ~45mph but can reach 60 mph Some danger for landing aircraft

29 FIRE DEVILS Spinning vortices of flames that move rather slowly igniting combustibles in their path Winds can exceed 100 mph, known to induce tornadoes Intense wildfires can induce them as can large scale conflagrations (Tokyo 1923, San Luis Obispo 1926, Hamburg, Dresden, Tokyo , Yosemite Rim Fire 2013)

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31 OROGRAPHIC WINDS Santa Ana winds Downslope winds Lee waves Rotor waves

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33 MORE CALIFORNIA WEATHER Clouds May Gray/June Gloom Visibility Marine fog Tule fog Sea haze Smog Lighting Refraction, reflection, scattering phenomena Earthquake lights Wildfires

34 MAY GRAY/JUNE GLOOM A Marine Layer effect A temperature inversion forms from air sinking from the North Pacific High Intensified by cold water of California Current La Niña strengthens the temperature contrast Low altitude stratus clouds form in the Marine Layer and move inland on a sea breeze

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36 CATALINA EDDY A counterclockwise vortex centered near Catalina Island Formed by diversion of NW winds into the Los Angeles basin Extends stratus cloud cover inland and increases its persistence

37 MORE CALIFORNIA WEATHER Lighting Refraction reflection, scattering phenomena Earthquake lights Wildfires

38 EARTHQUAKE LIGHTS Light displays associated with earthquakes Are they real? Apparently yes! Have been reported and recorded by observers considered to be reliable Napa quake August 2014 What causes them? No theories experimentally verified (yet)

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40 METEOROLOGY RESEARCH AT UCI Soroosh Sooroshian Hydrometeorology Department of Earth System Science Physical Climate 14 faculty 10 research staff Large number of students and postdocs 12 research groups

41 SAMPLE INTERESTS The impact of climate change on the water cycle Dynamics of atmospheric processes The role of ocean dynamics in the climate system Feedback between terrestrial ecosystems and climate The interaction of ice and climate The Greenland and Antarctic ice sheets Modeling of atmospheric processes Microphysics of atmosphere s interaction with trace gases, aerosols and surfaces Next generation climate simulation

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43 Please enjoy some fine summer weather wherever you go! I hope you will be able to enlarge the scope of your interest in the science of weather perhaps suggest some classes for OLLI? May we get the rain we need this Fall! (But not too much.)

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