Notes for
Meteorology 356
September 24, 2004
Anh Le
Valerie Low
Latest Surface Map (9:00am Pacific Time)
á Ivan was still a tropical storm this morning
- Map of Ivan shows no rainfall because the rainfall was between the weather stations
- The air was warm & moist with a lot of precipitation
á ThereÕs one big area of cumulonimbus monster thunderstorm around LA and TX border, this is a active storm and there will be more precipitation then expected
á Hurricanes float with winds just like wood floats in a river current
á A surface cyclone was shown drifting from west to east
- It was the same storm that we had in S.F.
á Front: the boundary between warm and cold air
- All fronts have cold air on one side and warm air on the other side.
- Cold Front: front which cold air is advancing into warm air.
- the blue triangles point to the direction which cold air is moving
- Similarly we have warm fronts, which warm air is advancing into cold
air instead.
- Stationary Front: The air is not moving; no air mass is advancing
- there are blue triangles & red semi-circle symbols
- cold air is coming in from one direction while warm air is coming in from the opposite direction
- Reason to plot Fronts:
- Short-term forecast technique, usually temperatures are likely to drop when we have cold fronts
- If moist, warm air is ahead of cold air, there will be lots of precipitation
á Ivan made a loop and came back around but weakened.
á Satellite
Image
o Ivan had no apparent eye
o The clouds were moving in a counter-clockwise direction
o There was one big area of cumulus nimbus clouds that made a shadow on the lower clouds.
á Jeanne Storm (link on the left-hand side of the page)
o Storms looping around
o Expected to come across Florida within the same areas that Francis hit
5 Day Precipitation Forecast
- lots of precipitation is expected in Florida
- in the past month, Florida received 14.9 inches of rain
Jet Stream Radar: active precipitation in U.S
- Radar calculates height of storms
- it is helpful so planes know whether to go under or over the storms
- Heaviest is at TX and LA ( since Ivan Hurricane is here)
- Cumulonimbus is higher than 44,000 ft
- Severe thunderstorm warning in the areas
(Flag symbol in a radar map doesnÕt indicate the wind direction; it points out the thunderstorm movement-where it comes from instead)
Mediterranean Climate
- Classified by the amount of rainfall each year
- Places like Italy, Greece, Portugal & North Africa have a Mediterranean climate
- Important Characteristics: The summers are dry and the winters are wet
SF ÒNormalÓ Rainfall
á we are in the western region climate center
á The numbers correspond to weather stations
- the Chronicle uses the weather station in Duboce Park (#8)
á 1971-2000 normals (link on left-hand side of page)
-NCDC (National Climate Data Center) – the US governments archive for free to anyone at an .edu website
- normal – the average of 30 years of weather information ending in decades (1971-2000, 1981-2010)