General

eGAFOR is a forecast of the meteorological impact on general aviation routes that will simultaneously, coordinately and harmoniously be produced in FIRs Zagreb, Belgrade, Bratislava, Bucharest, Budapest, Ljubljana and Sarajevo. Users can access the eGAFOR forecast via the webpage www.egafor.eu or met.crocontrol.hr/en/web/guest/egafor.

The following meteorological elements are forecasted in eGAFOR:

  • Clouds – BKN/OVC up to FL100
  • Visibility – Horizontal surface visibility below 8 km
  • Cumulonimbus – horizontal distribution of CB clouds
  • Turbulence – up to FL100
  • Freezing precipitation

Impact on routes

In the eGAFOR forecast, routes are colour-coded depending on the impact (forecasted meteorological impact on general aviation) that is determined from a probabilistic forecast of meteorological elements:

RED

Closed

ORANGE

Marginal conditions, not suitable for standard VFR operations, high level risk for aircrew under VFR conditions (high level of skills and knowledge of local conditions and terrain is a prerequisite)

YELLOW

Difficult weather condition for VFR operations (high level of skills and knowledge of local conditions is a prerequisite)

GREEN

Open

 

Time of issuance and validity period

 

The validity time of the eGAFOR forecast is 6 hours and it is divided into three 2-hourly intervals. For each time interval, a forecast is made which defines maximal impact in the interval.

Issuance time (UTC)

Validity period(UTC)

1. time interval

2. time interval

3. time interval

0200

03-05

05-07

07-09

0600

07-09

09-11

11-13

1000

11-13

13-15

15-17

1400

15-17

17-19

19-21

 

Depending on the duration of the illuminated part of the day, not all time intervals of the eGAFOR forecast may be issued. If a forecast has not been issued for a specific time or due to technical reasons, the whole area of the responsibility of a certain provider (e.g. FIR) will be greyed out for the selected time interval.

 

eGAFOR route network

The routes are harmonized on the whole domain. In Croatia, the eGAFOR route network consists of former GAFOR routes and connecting routes with neighbouring countries.

 

Route view and MET view

In the route view routes are colour-coded according to the forecasted impact. The route view is the default eGAFOR view.

Route view:

The MET view is the alternative view, in which the routes are grey with overlapped forecasted MET polygons. The polygons are coloured according to the MET element, while their pattern depends on a probability class.

MET view:

The content of eGAFOR and impact determination

Following MET elements are forecast in eGAFOR:

MET element

Acronym

Explanation

Polygon colour

BKN/OVC clouds

CLD

Cloudiness coverage more than 4/8

Green

Visibility

VIS

Horizontal visibility on the ground level below 8km

Yellow

Cumulonimbus clouds

CB

Horizontal distribution of CB clouds

Red

Turbulence

TURB

Turbulence in Low-Level Flight altitudes

Blue

Freezing precipitation

FZ PP

Any precipitation which freezes on contact with surfaces

Purple

 

MET elements are forecast as polygons and each polygon has a probability class assigned to it depending on the forecast probability:

Probability class

Probability

Polygon pattern

LOW

0 – 30%

Dotted

MEDIUM

30 – 70%

Line diagonal

HIGH

Above 70%

Solid

The impact on a route is determined for each MET element. The final element on the route is determined as maximal single impact.

Clouds

Clouds are forecast as a polygon with a relatively uniform ceiling. The probability class is determined from the expected cloud distribution within the polygon. The ceiling is given in ft AMSL with a vertical step of 100 ft. Due to the impossibility of determining the exact cloud base, an uncertainty zone has been introduced. The Uncertainty zone (UZ) is a zone between the minimal and maximal value of the forecast cloud base. The recommended UZ maximum is +/- 30% of the ceiling in AMSL, but not less than +/- 300 ft.

On the following image, a cross-section along a route (thin red line) and a ceiling UZ are displayed. In the example, the route is partly in the UZ.

Cloud impact is determined depending on whether at least part of the route is inside or above the UZ taking the probability class into account. The relation is shown in the table:

 

Bellow UZ

Inside UZ

Above UZ

LOW

 

 

 

MEDIUM

 

 

 

HIGH

 

 

 

 

Visibility

Visibility is forecasted in three classes:

  • Bellow 1.5 km
  • Between 1.5 and 5 km
  • Between 5 and 8 km

Visibility impact on a route is determined between visibility and probability classes as shown in the table:

 

<1.5 km

1.5 km – 5 km

5 km - 8 km

LOW

 

 

 

MEDIUM

 

 

 

HIGH

 

 

 

 

 

Cumulonimbus clouds

The horizontal distribution of Cumulonimbus clouds is forecast in three severity classes:

  • ISOL
  • OCNL
  • EMBD/FRQ/SQL

CB implies TS, GR, MOD or SEV TURB, ICE.

EMBD implies that Cumulonimbus clouds are embedded in another BKN/OVC cloud layer.

Cumulonimbus impact on a route is determined between severity and probability classes as shown in the table:

 

EMBD/FRQ/SQL

OCNL

ISOL

LOW

 

 

 

MEDIUM

 

 

 

HIGH

 

 

 

 

Turbulence

Turbulence is forecasted in two severity classes:

  • MOD (moderate)
  • SEV (severe)

Besides the severity class, the upper and lower boundary of a turbulent layer is being forecast in ft AMSL in 1000 ft steps.

The turbulence impact on a route is determined between severity and probability classes as shown in the table:

 

SEV

MOD

LOW

 

 

MEDIUM

 

 

HIGH

 

 

 

Freezing precipitation

Any amount of freezing precipitation is forecasted without severity classes.

The freezing precipitation impact on a route is determined depending on probability classes as shown in the table:

 

FZ PP

LOW

 

MEDIUM

 

HIGH

 

 

Općenito

eGAFOR je prognoza meteorološkog utjecaja na rutama za generalnu avijaciju koja se simultano, koordinirano i harmonizirano proizvodi u FIR-ovima Zagreb, Beograd, Bratislava, Bukurešt, Budimpešta, Ljubljana i Sarajevo. Korisnici prognozi eGAFOR pristupaju putem stranice www.egafor.eu ili met.crocontrol.hr/hr/web/guest/egafor.

U eGAFOR-u se prognoziraju slijedeći meteorološki elementi:

  • Oblaci - BKN/OVC do FL100
  • Vidljivost - Prizemna horizontalna vidljivost manja od 8 km
  • Kumulonimbusi - horizontalna rasprostranjenost CB oblaka
  • Turbulencija -  do FL100
  • Prehladna oborina

Meteorološki utjecaj na rutama

Rute su u eGAFOR prognozi obojene ovisno o prognoziranom meteorološkom utjecaju na generalnu avijaciju koji se određuje na osnovu probabilističkih prognoza meteoroloških elemenata.

CRVENO

Zatvoreno

NARANČASTO

Rubni uvjeti, nije prikladno za standardne VFR operacije, visoka razina rizika za posadu u VFR uvjetima (potrebna je visoka razina vještine, te poznavanje lokalnih uvjeta i terena)

ŽUTO

Otežani vremenski uvjeti za VFR operacije (potrebna je visoka razina vještine, te poznavanje lokalnih uvjeta)

ZELENO

Otvoreno

 

Raspored izdavanja i trajanje eGAFOR prognoze

eGAFOR je šestosatna prognoza podijeljena u 3 dvosatna intervala. Za svaki vremenski interval izrađuje se prognoza iz koje se određuje maksimalni meteorološki utjecaj u tom intervalu.

Vrijeme izdavanja (UTC)

Period važenja (UTC)

1. vremenski interval

2. vremenski interval

3. vremenski interval

0200

03-05

05-07

07-09

0600

07-09

09-11

11-13

1000

11-13

13-15

15-17

1400

15-17

17-19

19-21

 

Ovisno o trajanju osvijetljenog dijela dana, neki vremenski intervali eGAFOR-a se mogu ne izdavati. Ukoliko prognoza nije izdana na području jednog FIR-a, u tom vremenskom intervalu područje tog FIR-a bit će sivo.

Mreža eGAFOR ruta

Rute su harmonizirane na cijeloj domeni. U Hrvatskoj se mreža eGAFOR ruta sastoji od dosadašnjih GAFOR ruta i spojnica s rutama u susjednim zemljama.

Rutni prikaz i MET prikaz

Zadani prikaz eGAFOR-a je rutni prikaz, odnosno prikaz prognoziranog meteorološkog utjecaja na generalnu avijaciju na rutama. U rutnom su prikazu rute semaforski obojene ovisno o meteorološkom utjecaju.

Rutni prikaz:

Alternativni prikaz je MET prikaz u kojem su rute sive, a prikazani su prognozirani MET poligoni na temelju kojih je određen meteorološki utjecaj. Poligoni su obojani ovisno o MET elementu, a uzorak im ovisi o klasi vjerojatnosti.

MET prikaz:

 

Sadržaj eGAFOR-a i određivanje impakta

U eGAFOR-u se prognoziraju slijedeći MET elementi:

MET element

Kratica

Objašnjenje

Boja poligona

Oblaci BKN/OVC

CLD

Naoblaka iznad 4/8 stropnice do FL100

Zelena

Vidljivost

VIS

Prizemna horizontalna vidljivost manja od 8 km

Žuta

Kumulonimbusi

CB

Horizontalna rasprostranjenost CB oblaka

Crvena

Turbulencija

TURB

Turbulencija do FL100

Plava

Prehladna oborina

FZ PP

Bilo koja oborina koja se smrzava na površinama

Ljubičasta

 

MET elementi se prognoziraju kao poligoni i pritom se svakom poligonu pridružuje klasa vjerojatnosti koja govori o vjerojatnosti ostvarenja prognoze:

Klasa vjerojatnosti

Vjerojatnost

Uzorak poligona

Niska (LOW)

0 – 30%

Točkasti

Srednja (MEDIUM)

30 – 70%

Koso prugasti

Visoka (HIGH)

Više od 70%

Puni

 

Utjecaj na pojedinu rutu se određuje za svaki pojedini MET element. Konačni utjecaj na ruti se određuje kao najveći pojedini utjecaj.

Oblaci

Oblaci (CLD) se prognoziraju kao poligon s relativno ujednačenom stropnicom. Klasa vjerojatnosti proizlazi iz očekivane rasprostranjenosti oblaka unutar poligona. Stropnica se iskazuje u ft AMSL s vertikalnim korakom 100 ft. Zbog nemogućnosti preciznog prognoziranja točne visine stropnice, uveden je termin „zona nesigurnosti" (Uncertainty Zone – UZ). UZ je raspon između minimalne i maksimalne visine očekivane stropnice za određeni sloj oblaka. Preporučeni maksimum UZ-a je +/- 30% stropnice u AMSL, ali ne manje od +/-300 ft.

Na slijedećoj slici dat je prikaz presjeka terena uzduž rute (ovdje tanka crvena crta) i UZ oblaka. U primjeru na slici sama ruta se jednim dijelom nalazi unutar UZ.

Utjecaj oblaka na ruti se određuje prema tome nalazi li se bar neki dio rute unutar ili iznad UZ uz uvažavanje klase vjerojatnosti. Odnosi su prikazani u tablici:

 

Ispod UZ

Unutar UZ

Iznad UZ

LOW

 

 

 

MEDIUM

 

 

 

HIGH

 

 

 

 

Vidljivost

Vidljivost (VIS) se prognozira u tri klase:

  • Ispod 1.5 km
  • Između 1.5 i 5 km
  • Između 5 i 8 km

Utjecaj vidljivosti na ruti se određuje iz odnosa klase vidljivosti i klase vjerojatnosti na način kako je prikazano u tablici:

 

<1.5 km

1.5 km – 5 km

5 km - 8 km

LOW

 

 

 

MEDIUM

 

 

 

HIGH

 

 

 

 

Kumulonimbusi

Horizontalna rasprostranjenost kumulonimbus oblaka (CB) se prognozira u tri klase jačine:

  • ISOL
  • OCNL
  • EMBD/FRQ/SQL

CB implicira i TS, GR, MOD ili SEV TURB, ICE.

EMBD ovdje znači da su kumulonimbusi uklopljeni u bilo koji sloj BKN odnosno OVC oblaka.

Utjecaj kumulonimbusa na ruti se određuje iz odnosa klase jačine i klase vjerojatnosti na način kako je prikazano u tablici:

 

EMBD/FRQ/SQL

OCNL

ISOL

LOW

 

 

 

MEDIUM

 

 

 

HIGH

 

 

 

 

Turbulencija

Turbulencija (TURB) se prognozira u dvije klase jačine:

  • MOD (umjerena)
  • SEV (jaka)

 Uz klase jačine, prognoziraju se i gornja i donja granica sloja TURB u ft AMSL, s korakom 1000 ft.

Utjecaj turbulencije na ruti se određuje iz odnosa klase jačine i klase vjerojatnosti na način kako je prikazano u tablici:

 

SEV

MOD

LOW

 

 

MEDIUM

 

 

HIGH

 

 

 

Prehladna oborina

Prognozira se bilo koja količina prehladne oborine, bez klasa jačine.

Utjecaj prehladne oborine na ruti se određuje iz odnosa klase vjerojatnosti na način kako je prikazano u tablici:

 

FZ PP

LOW

 

MEDIUM

 

HIGH