26

In the US, meteorologists forecast the probability of ANY amount of precipitation falling. The minimum amount of that we deem acceptable to meet this criteria is .01". So, we are forecasting the probability of one hundredth of an inch of precipitation to fall at a location. We look at observational data from ground stations, satellites, and computer ...


20

The Cascade Mountain Range in the US Pacific Northwest is a good example to use to explain this. The predominant wind direction is from the West - over the Pacific Ocean. The air over the ocean picks up moisture from evaporation. After it passes the coast, the mountains cause the air to rise. As it does so it cools. Colder air can hold less water vapour than ...


18

There is more to phase change than just what you see on that graph. At temperatures and pressures that support multiple states (e.g. solid and gas) you have to look at the saturation vapor pressure of the gas and the actual vapor pressure (partial pressure) of the gas -- the line on the graph represents equilibrium between the states. The differences ...


16

Yes. Nearly global satellite and radar derived rainfall data are hosted by NASA Goddard Space Flight Center, namely: Tropical Rainfall Measurement Mission (TRMM) aboard the TRMM Microwave Imager (TMI), a multi-channel, dual polarized, conical scanning passive microwave radiometer designed to measure rain rates over a wide swath under the TRMM satellite. ...


13

The key is with wind-drifting. The predominant westerlies cause snow to drift into protected places. We should perhaps recall that glaciers exist because they are essentially snow-catchers in a landscape that is sufficiently suitable for some of the snow to survive the summer melt period. The drifting and depositing of snow on the eastern side of mountains ...


13

If you are looking for a dataset going back a bit further, but still sticking to satellite and radar data, GPCP (Global Precipitation Climatology Project) goes back to 1979. The limitation of certain TRMM datasets, in addition to the relatively short length of the project, is that they only cover the tropics and so you lack data in the mid-latitudes and ...


13

Your question is fairly broad, and slightly vague so I don't know if I will be able to answer it in one go. If you would like any clarification, let me know. How are predictions made? The basic process generally used for probabilistic forecasting of the global climate is something like: Take one or more general circulation models (GCMs), and run multiple ...


12

Extratropical cyclones in the Northern Hemisphere rotate around the earth in the mid-latitudes in a mean westerly flow. This means that, on average, the track of a storm between 30°-60°N moves from west to east. Ahead of these extratropical cyclones is a strong frontal boundary with very powerful winds, sometimes up to hurricane strength near the boundary ...


12

The bulk of the planet's precipitation falls from convective storms that develop throughout the Intertropical Convergence Zone (ITCZ). The ITCZ transits north and south of the equator due tracking the sun's zenith throughout the year and is skewed by the position of land, but is generally situated near the equator over the ocean. Trenberth et al (2006) go ...


10

The snow density, which is the "conversion function" you are looking for, of fresh fallen snow varies with atmospheric conditions, vapour saturation and temperature since these parameters determine the snow grain morphology (See this figure from SnowCrystals.com; I leave it as a link for copyright reasons). Densities can vary from as low as < 100 kg m-3 ...


10

The probability of precipitation is most likely to mean the proportion of models in an ensemble or weather models in which precipitation was observed at a particular location over in particular time period. If you want to work out the probability of it raining during the day, the best approach would be to work out one minus the probability that there was ...


9

It is likely snowing somewhere in these clouds and graupel exist transiently on their way to becoming hail, but its not likely that you will see either at the surface. You can make a first order approximation of a pyrocumulus cloud by putting a very strong heat source at the surface in an environment otherwise favorable for severe convection. What you'll ...


9

First off, your observation that Tamil Nadu gets more rainfall in the evening is partially backed by records. Sahany, Venugopal, and Nanjundiah, 2010 provide data on diurnal scale rainfall distribution during the Southwest monsoon season shows that Tamil Nadu is dry from 0530-1430 each day, and likely to be wet from 1730-0230: The Northeast monsoon is ...


8

WorldClim is an alternative. It is a set of climate layers with spatial resolution of 1 square kilometer. It provides current conditions, forecast and historical data. Besides rainfall there are data available for Min. Temperature, Temperature, Mean Temperature, Bioclim and Altitude. Data is divided in tiles and available in GeoTiff or ESRI grid format.


8

There is a case study from Environmental Science entitled El Niño: A Link among Atmospheric, Oceanic, and Crustal Circulation? that discusses the correlations between seismic activity and El Niño cycles in certain areas of the world, that have been documented: A geophysicist, Daniel A. Walker, hypothesizes that a different sequence of events produces an ...


8

@Peter Jansson provides a much more thorough answer, but for a quick conversion of expected liquid water equivalent to expected snow depth: 1 inch liquid water = 10 inches snow for warm storms 1 inch liquid water = 20 inches snow for cold storms or 25 mm = 25 cm for warm storms 25 mm = 50 cm for cold storms Often a certain climatology will trend one ...


8

I'll augment the other answer with an example. Consider a theoretical north-south oriented mountain range that rises 2000 m above sea level and the land on either side of the range is at sea level. A little ways west of the mountain is ocean. The location is the mid-latitudes and the prevailing wind is from the west. Air along the surface travels above ...


8

TLDR; The precipitation values (and possibly some other variables; see below) need to be divided by 24. Background The global attributes of the netCDF file in the question provide an URL to a description page: coastmod.hzg.de From that URL a user should be redirected to wiki.coast.hzg.de/display/MD (access at 9th Feb 2018). Unfortunately, the redirect ...


7

700 m elevation difference on the windward side will be definitely enough to trigger orographic influences on precipitation. Thus from your description it seems very plausible that the mountains influence the precipitation you get.


7

There isn't a risk to putting it out other than the attempt failing, it is just impractical to do so once a large coal vein catches fire. You can read more about the Centralia, PA coal fire on wikipedia which sits on top of anthracite coal veins that have been burning for a little over 50 years and are likely to continue to do so for a few hundred years. ...


6

This is an El Nino summer, and a very strong one and a very weird one at that. Weather patterns are messed up world-wide. Apparently a stable high pressure cell has set up that oscillates back and forth between just east of Barcelona to eastern Europe. France suffers when that high pressure cell is just east of Barcelona. That high pressure cell off ...


6

First of all, these netCDF files follow the CF Metadata Conventions, which describe the use of scale_factor and add_offset in section 8.1 Packed data of the conventions description. In short, you're applying them correctly: If both attributes are present, the data are scaled before the offset is added. However, I think that you've selected the wrong ...


6

If you take a look at the atmospheric circulation pattern, the Hadley Cells in particular, they tell the story. The northern edge of Africa is on the descending edge of a Hadley Cell, which means Having lost most of its water vapor to condensation and precipitation in the upward branch of the Hadley cell circulation, the descending air is dry. As the ...


6

UserLTK, above, has mentioned the Dry Valleys of Antarctica and the Atacama desert as two notable examples of "permanent" deserts. It's likely that these two locations have been deserts for at lease several millions of years despite changes in global weather patterns from multiple glacial events. The Atacama is well shielded by a very old mountain range to ...


5

It literally means that the water depth will be 0.5mm. For example, if you place a container under the rain and it fills up to 0.5mm, then the precipitation is 0.5mm. Despite the fact that a wide container requires more rain to fill up than a narrow container, the larger surface area allows it to collect the right amount of rain water to fill up to the same ...


5

For an example of how bad agricultural practices can cause soil loss and end up with dust and sand, see the conditions that preceded the dust bowl in the USA. Certain crops are bad for soil and if not rotated will eventually deplete the soil of nutrients leading to no crops. With nothing holding the soil in place (roots) it will erode. The Sahara has other ...


5

I'm not aware of any datasets that are quite what you want (archived point forecasts for the next day). There is less digestible data out there though. NOAA NCDC archived messages This website has archives of all messages that NOAA transmits. The vast majority are unrelated to your needs, but if you look through the message types you might find something ...


5

Farrenthorpe is right, a little surfing the net for snow distribution would clarify the picture for you. However, I think you are referring to certain times when it rains further north and snows further south. There are several reasons for local anomalies, of which the most important is the dynamics of the polar jet streams. These are strong high-altitude ...


5

The US NCDC has this link to surface hourly global data which I was indeed able to find Napoli on. It appears, based upon this page describing the World Data Center For Meteorology, that there may be restrictions on using the data commercially outside of the United States.


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