Questions tagged [weather-forecasting]

Questions about the application of weather data in meteorology/forecasting.

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3
votes
1answer
91 views

How long does it take to refresh the entire water supply in the Earth's atmosphere?

Water in the atmosphere is present as vapour, liquid and ice. It is just a small amount of the Earth's total water supply. I'm wondering how long it will take to rain down all the water from the ...
7
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3answers
153 views

Why don't weather forecast models normally take solar eclipses into account?

Since there is a total solar eclipse somewhere almost every year, I would have thought it would be included as a standard option in weather forecast models. However, I've learned that is not really ...
3
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2answers
222 views

How much is Solar Radiation effected by Axial Tilt or Obliquity?

I know that the Axial Tilt of Earth is about 23.4° - 23.5°. And I would like to know how much this change effects Solar Radiation for particular geo-location. What is the Axial Tile change rate? How ...
1
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2answers
1k views

How to calculate air temperature for given time, location and altitude?

I would like to calculate (estimate) air temperature at given time, location and altitude. All I have is air pressure for 20°C. The formula based on NTP (Normal Temperature and Pressure) to calculate ...
4
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1answer
65 views

Freely available and re-distributable weather observations over the US?

I am looking for a (small) data set of weather observations for a few (say 5-20) weather stations in the US, with observations of precipitation, temperature and wind speed for the year 2016. The data ...
2
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2answers
593 views

How do I convert a latitude/longitude coordinate to a NOAA GFS grid cell location?

Looking at this GFS http://nomads.ncep.noaa.gov:9090/dods/gfs_0p50/gfs20170707/gfs_0p50_12z.ascii?tmax2m[0:2][124:128][279:283] The range defined by the second and third set of brackets specify the ...
3
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1answer
565 views

How to properly setup a domain in NWP model (WRF) according to meteorological input data

I want to setup a mesoscale weather prediction model (WRF or something else) to work with NCEP/GFS meteorological input data with resolution of 0.25deg. My question is how to choose a proper size for ...
3
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1answer
597 views

How to calculate 3-hour flux values in ERA-Interim?

Referring to the post: https://www.myroms.org/forum/viewtopic.php?f=30&t=3003 I understood how to calculate the slhf and sshf for 03, 06, 09 and 12 time steps. But I have values for 00, 15, 18 ...
4
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1answer
112 views

ISA Model and GFS data

I have a newbie question... I always used the International Standard Atmosphere model whenever I needed to calculate the temperature in a given altitude. It always looked accurate to me... However,...
2
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0answers
344 views

Do U & V vectors differ depending on GRIB layers (wind vs current)?

Essentially I would like to know how current direction "DIR C" and wind direction "WDIR" for gribs is computed. I'm trying to compute some angles from u and v vectors in grib files. My understanding ...
7
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2answers
717 views

Calculate the latitudes of a Gaussian Grid

I would like to calculate the latitude values of a Gaussian Grid of a size of my choosing. Unfortunately, I didn't find a method or a formula to do so. Where can I find this information? Alternatively,...
3
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0answers
373 views

Learn weather forecast

Is there any website for videos/articles that explains how to read maps or other graphics use to make forecast prediction (more advanced than the weather channel please) ? It could be about any ...
2
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1answer
357 views

upper air data(observation) and analysis step for GFS model

Global forecast systems(GFS) gives analysis and forecasts at different time steps. Their main source of input is upper air data which is recorded only twice in a day(observation comes at 00 and 12). ...
2
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1answer
384 views

How can I learn to make mesoscale/synoptic analyses of major weather events?

With the tornado outbreak in southern Georgia and northern/central Florida on Sunday that has tragically resulted in significant loss of life, eyes are once again on the weather. I was particularly ...
5
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2answers
319 views

Is there a standardized way to define weather icons based on quantifiable data?

Weather APIs often provide weather icons which symbolize the state of the sky at a given point, or as an average. Is there a standardized way to define what the icon should be, based on quantifiable ...
19
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1answer
1k views

What is this “crystal ball” located at a meteorological station?

I found what looks like a "crystal ball" in a meteorological station in the Vlădeasa mountains (Romania). What is its purpose?
2
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0answers
49 views

What kind of storm tracks produce snow in the eastern United States?

What storm tracks are favorable for snow in the eastern United States? Articles like this one on a winter storm in the Northeast in 2011 indicate that storm tracks are important in snowfall amounts. ...
4
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1answer
198 views

Global Gridded Daily Temperature (at 2m): difference between GEFS Reforcast and NCEP Reanalysis

I am looking for gridded/raster estimates of daily mean temperature (ideally ambient/at 2 meter) for a public health analysis. Specifically, I want to correlate daily mortality counts with daily mean ...
6
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1answer
6k views

Is it typically colder after a storm?

I've heard that it's colder after a storm. I think this is an interesting question, not least because of the implicit comparison: colder than what? A few different comparisons come to mind, and still ...
1
vote
1answer
121 views

How can I implement a visualization of archived convective data from numerical weather models?

I've always found geographic visualizations of surface/mixed-layer CAPE models and other weather data to be incredibly interesting. Here's a map featured by the Capital Weather Gang over at the ...
5
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1answer
74 views

Can the forecast N+1 days ahead be more certain than the forecast N days ahead?

The Swedish meteorological agency SMHI on its website (NB: freezes Firefox on Linux for me, likely due to plugins, works in Chrome) indicates how certain the forecast for a particular day is. Looking ...
4
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2answers
189 views

Are we changing Earth's weather with global warming?

I think that when the air heats up in the day, the radiation from the ground contributes way more to its heating at altitudes more than 300 meters above the ground than convection currents of air heat ...
6
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3answers
406 views

Publicly available data set with ensemble forecasts and observations?

I am looking for a publicly available, easy to download, small data set of ensemble forecasts (or reforecasts), with corresponding observations or reanalysis. We are planning to illustrate some ...
1
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1answer
97 views

Could a large burst of super-heated or super-cooled air cause tornadoes to fall apart?

We know how tornadoes form: when areas of hot air and cold air mingle, causing rotation. We can even see them form on the radar. Yet, for all of our technology, we can't stop such events from ...
5
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0answers
580 views

Why did the GFS switch to hourly forecasts through hour 120?

About a month ago, the GFS was upgraded. Among other things (like making parallel GFS data available), the upgrade notice said: Include hourly forecasts out to 120 hr Now, this seemed ...
4
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2answers
4k views

Interpolate Gaussian grids to regular fixed grids using bilinear interpolation?

I want to regrid GCM data available on Gaussian grids to regular grids, say at 1 deg X 1 deg. How to do this using CDO or Python ...
-1
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1answer
276 views

Temperature Fluctuation in a Day

I was looking at the temperature plots in Nashik, India and noticed an intriguing trend. What could explain this trend? [screenshot from WeatherUnderground forecast] Shouldn't the plot be smoother? ...
6
votes
1answer
166 views

Why do forecast areas on weather.gov appear as twisted squares?

I get my weather forecasts from good ol' NOAA's weather.gov site. On the detailed site weather pages, there's a map that shows the forecast area as a green square (for Boston at least, the square is ...
5
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1answer
250 views

What is the difference between the freezing level and 0C isotherm in NOAA's GFS?

I'm playing around with NOAA's GFS forecast data and I see that it contains both a "0C isotherm level" and a "Highest tropospheric freezing level". Could someone tell me the difference between these ...
7
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2answers
781 views

Long-term Wind Speed Forecasting: reality or wishful thinking?

I have been studying/working with Wind Energy for a while and, one of my main responsabilities right now is to search for adequate long-term wind speed forecasting models. However, 2 things strike me ...
7
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2answers
1k views

Help interpreting a wind rose diagram

Can someone comment on technical explanation of the wind rose attached? I can understand the wind is blowing between WNW & SSW with speed of 7-11 km/h. For frequency of 11-16 km/h its blowing ...
4
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1answer
131 views

Best sources / methods to find additional cloud information for current weather conditions?

I posted this question on Aviation Stack Exchange here. One of the responses suggested that I post my question on Earth Science Stack Exchange. I need a source that reports necessary current cloud ...
6
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0answers
81 views

Worldwide weather maps database

I am searching for a database (a free one would be great) that would give me, for any chosen rectangular area on earth, historic data about pressure, sea water temperature, wind (including both speed ...
1
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0answers
102 views

Sailing Around the World on a Jet Stream

An ultra light plane can stay in flight up to 2400 km (the World Record) with out an engine using thermal lift. Can a huge kite like airship (not a blimp) be built to indefinitely sail in and out of ...
4
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2answers
1k views

Historical NWS GFS forecast data

The National Weather Service (NWS) makes the results from its Global Forecast System model (GFS) available for download as GRIB2 files. While accessing current (or recent) forecasts is straight-...
4
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2answers
127 views

Need help understanding variables that relate to meterology terminology

I am working on a project in predicting the weather and I had a few brief questions. I understand that radar works by bouncing waves off of precipitation and measuring reflectivity. I have a variable ...
2
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2answers
144 views

Global warming and winter temperatures

What causes cold temperatures to move earlier than they usually move? Here in Buffalo the weather was 9 °C. However, everyone had winter coats and hats on. There was no snow, but it was very very ...
8
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1answer
103 views

Are the storm cones introduced by Robert Fitzroy still in use?

In 1860 or so, following the tragic wreck of the Royal Charter with the loss of over 400 lives, storm cones were installed in many UK ports, under the direction of Admiral Fitzroy, head of the ...
4
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1answer
253 views

Why is it always rainy in Addis Ababa?

I watch the news and in the weather forecast it's always rainy in central Africa, especially in Addis Ababa. Why is that?
5
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0answers
102 views

Initial indexes for calculating the Fire Weather Index (in the Canadian Forest Fire Weather Index System)

I am applying the Canadian Fire Weather Index (FWI) on the Forest Fire Warning System of my laboratory. My problem is in calculating the Fine Fuel Moisture Code (FFMC), the Duff Moisture Code (DMC) ...
7
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3answers
480 views

Algorithmically Determining the Rainy Season

I have historical precipitation data for hundreds of cities around the world. I would like to algorithmically determine when the rainy season (if exists) is for each location. Are there any algorithms ...
13
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2answers
2k views

How to interpret hourly precipitation forecast?

How should I interpret the hourly precipitation forecasts? Most of the time, when there is rain in the forecast, the maximum Probability of Precipitation (PoP) in the hourly forecast is about the ...
8
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3answers
431 views

Predicting school closures with historical weather prediction data?

I'm interested in predicting when the local schools will be closed due to snow and other winter weather. I have a list of school closure dates and a rough sense of the criteria used to determine the ...
7
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1answer
859 views

Statistical weather prediction

Assuming I have time evolution of air temperature, air pressure, wind speed, wind direction, relative humidity and cloudiness, how can I predict weather based on this information? I know that high ...
11
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1answer
2k views

Intuitive explanation of precipitation amount

I'm trying to learn how to make sense of numbers in a forecast. I can interpret temperature and wind speed, but I don't know what to make of rainfall. What does it mean, for a human, that there will ...
14
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1answer
4k views

What is the meaning of -999 degrees Celsius?

I was checking the weather forecast just now, and it is showing that it "feels like -999 °C". I never heard or saw -999 °C before. I searched other weather channels, and they were showing that it ...
11
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1answer
447 views

What does the term “Snow Interval” mean?

When looking Weather Station readings from the National Weather Service website, what does the term "Snow Interval (inches)" actually mean? 6 hr and 24 hr readings are obvious, but I can't seem to ...
5
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1answer
444 views

How do I interpret the specs of a weather balloon?

I'm planning a high-altitude weather balloon project (to around 100000 feet, or 30 km) some time down the line to take video and pictures of near space altitudes and I have some questions I need to ...
18
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2answers
5k views

What are the applications of hydrostatic solvers vs non-hydrostatic solvers in numerical weather prediction?

In the atmospheric dynamics research community, many colleagues of mine happen to use atmospheric models that have non-hydrostatic equation solvers, e.g. the UK MetOffice model, and WRF-ARW: The ...
20
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1answer
759 views

What data does a skilled meteorologist look at to predict thunderstorms?

An uneducated layman like me would just look at CAPE numbers and make rough guesses on possible thunderstorms. In a related but non-duplicate question, vertical wind shear is discussed. If we are ...