GFS maps: Italy, Humidity and Vertical Velocity at 850 hPa
Humidity and Vertical Velocity at 850 hPa: analysis and forecast
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| Geop.+Temp. 500 hPa | 2 m Temperature | 500 hPa Temp. Anomalies | Rain & Snow + 0 C Level | 10 m Wind | Cloud Cover |
| Geop. + Temp. 500 hPa (GIF) | Minimum Temperature | 2 m Temp. Anomalies | 1 Day Total Precipitation | 500 hPa Wind | CAPE & Lifted Index |
| Geop.+Temp. 850 hPa | Maximum Temperature | Daily 2 m Average Temp. | Precipitable Water | 200 hPa Jet Stream | CIN |
| Geop. + Temp. 850 hPa (GIF) | 2 m Temp. trend | Daily 2 m Temp. Anomalies | RH + Vertical Vel. 850 hPa | 300 hPa Jet Stream | 500 hPa Forecast Stability |
| Geop.+Temp. 925 hPa | 850 hPa Temp. trend | Daily 850 hPa Average Temp. | RH + Vel. Verticale 700 hPa | 850 hPa Forecast Stability | |
| 500 hPa Geop. + Temp. trend | 850 hPa Temp. Anomalies | Daily 850 hPa Temp. Anomalies | RH + Vel. Verticale 500 hPa | Last 4 GFS run comparison |
GFS Italy: Relative Humidity [%] and Vertical Velocity [Pa/s] at 850 hPa
These maps show the relative humidity (in %) and the vertical baric velocities (in Pa/s) at a 850 hPa pressure level,
corresponding to an altitude of about 1500 m (see the geopotential maps). The formation of low clouds in an area
occurs with high relative humidity values and negative vertical (omega) velocities. Humidity close to 100% is not necessary if at the same time there
are sufficient ascending motions (negative vertical speeds) which, cooling by expansion, can bring the air to saturation. Here are 3 conditions for
which an overcast sky is expected: 1) RH=60÷80%, Ω <-0.4 Pa/s;
2) RH>80%, Ω<-0.3 Pa/s; 3) RH>90%, Ω=-0.3÷0 Pa/s.
On the top left is shown the UTC initialization time. UTC time is indicated with Z letter (Zulu Time).
On the top right is shown the UTC forecast time.
The maps at 00Z, 06Z, 12Z and 18Z are updated respectively starting from 04.30 AM, 10:30 AM, 4:30 PM, 10.30 PM (CEST TIime).
Forecast model: Global Forecast System (GFS) with 0.25°x0.25° (lat x lon) spatial resolution.
NOTE: in central European countries, when solar time is in effect, the CET time is used, which is equal to UTC +1 hour, while when daylight saving time is in effect, the CEST time is used, which is equal to UTC +2 hours. Right now it is 4:00 UTC.
Notes on GFS forecast maps
The Global Forecast System (GFS) is a National Centers for Environmental Prediction (NCEP)
weather forecast model that generates data for dozens of atmospheric and land-soil variables,
including temperatures, winds, precipitation, soil moisture, and atmospheric ozone concentration.
The system couples four separate models (atmosphere, ocean model, land/soil model, and sea ice) that work
together to accurately depict weather conditions.
GFS is a global model with a base horizontal resolution of 0.25° (28 kilometers) between grid points.
The GFS is run 4 times a day, the temporal resolution covers analysis and forecasts out to 16 days.
See the GFS analysis maps archive from 2013 to today
To see the GFS ANALYSIS MAP ARCHIVE from 2013 to today click on the red link.