How is PlaneWX different from my EFB or aviationweather.gov?

Your EFB is excellent for charts, filing, and day-of flying. Aviationweather.gov and Flight Service (including 1800WXBRIEF) give you official weather products. PlaneWX sits beside those tools. It does not replace them. What PlaneWX adds is decision support days out: a WX Score matched to your aircraft and personal minimums, a dynamic FRAT on the FAA PAVE framework, and mentors who see the same briefing you see. You can also share a flight plan into PlaneWX from a supported EFB. You stay PIC. Charts, filing, and official sources stay where they belong.

Is the briefing accurate?

Your briefing uses the same official observations and forecasts every pilot relies on: METARs, TAFs, PIREPs, SIGMETs and model guidance. It can only be as accurate as those forecasts, and every forecast carries some uncertainty. Every weather briefing, from any provider, also has the same built-in limit. It describes one departure time, one route, one altitude and one arrival time. Real flights change. You leave late, get rerouted, or get assigned a different altitude, and each change puts you in weather the briefing didn't look at. That's why PlaneWX can keep updating your briefing for monitored flights as the forecast changes, and why your decision-making continues in the air.

How can I make my briefing more accurate?

Enter the flight the way you'll really fly it: a realistic departure time, the route you expect to file or be cleared, your planned altitude, and the right aircraft profile. If any of those change, update the trip and brief again. Check again close to departure, when the forecasts are freshest.

Yes, in specific places. Weather reports, forecasts, model data and NOTAMs are fetched and decoded by code. AI reads forecaster discussions and writes the plain-language briefing, the hazard summary and most section ratings. It also proposes a starting WX Score and some deductions, such as for convection. Ceiling and visibility are always scored by code. Within 12 hours of departure, your personal minimums and aircraft limits are checked by rule-based code, not the AI. Further out, AI also helps weigh icing and turbulence against your limits. You always make the final call.

What is the WX Score?

The WX Score is a 0-100% metric calculated against YOUR personal minimums and your specific aircraft, not generic VFR/IFR categories. It tells you, in a single number, how well conditions are expected to match your standards. Every deduction is transparent and explained.

What is the PAVE framework?

PAVE is the FAA risk framework: Pilot, Aircraft, enVironment, and External pressures. It is the structure behind a serious preflight risk assessment, not a weather product by itself. We walk through it in plain language in our PAVE risk assessment guide. PlaneWX FRAT uses that same framework as a living sit-down assessment near departure. See how PlaneWX FRAT works, including how the briefing and airport context feed the enVironment side.

How far in advance can PlaneWX forecast weather?

PlaneWX provides weather intelligence from 14 days out through departure. Confidence improves as your flight approaches. We are transparent about uncertainty at every time horizon.

What is the mentor system?

PlaneWX connects you with experienced pilots who can review your full briefing (WX Score, aircraft profile, personal minimums) and offer a second set of eyes grounded in shared data, not guesswork. Mentor sits alongside the risk-management loop when you want it.

Is there a free plan?

Yes. Free forever includes full-quality briefings. We limit how much you can use PlaneWX, not how good the analysis is. Details on plans and what each tier includes are in PlaneWX Plans help.

What's the difference between Casual, Pro, and Pro Plus?

Casual is for pilots who fly a few times a month and want auto-monitoring. Pro raises limits and automation. Pro Plus adds Ground Protection, Auto-Brief, Pre-Flight Text, briefed fuel stops, and Labs. Compare current limits and features in Plans help, or start from the pricing section on this page. Personal minimums still drive the WX Score on every plan. If you are setting those for the first time, see personal minimums for weather planning.

What happens after the 14-day free trial?

You keep access on Free, or choose Casual, Pro, or Pro Plus. No card is required to start the trial. Plan details stay in Plans help.

Turbulence Forecasts: GTG, GTG-N, and the Intensity Scale

PlaneWX · Updated September 29, 2026

GTG (Graphical Turbulence Guidance) is the NWS automated forecast of clear air and mountain wave turbulence, issued every hour out to 18 hours from 1,000 ft MSL to FL450. GTG-N is its nowcast, updated every 15 minutes. Both express turbulence as EDR, and neither replaces AIRMETs, SIGMETs, or PIREPs [1, paras. 25.6 and 27.14].

Key takeaways

GTG forecasts clear air and mountain wave turbulence. It does not forecast thunderstorm turbulence or small-scale terrain effects [1, para. 27.14].
GTG is scaled by aircraft weight. A light airplane should read the light class, under 15,500 lb [1, para. 27.14].
Turbulence intensity is defined by what the aircraft does: light, moderate, severe, or extreme [3, para. 7-1-21].

Key facts

GTG is the NWS automated forecast of clear air and mountain wave turbulence [1, para. 27.14].
It is issued hourly: hourly forecasts for 3 hours, then every 3 hours through 18 hours [1, para. 27.14].
GTG covers 1,000 ft MSL through FL450 and is scaled to light, medium, and heavy aircraft [1, para. 27.14].
GTG does not forecast convective or small-scale terrain turbulence [1, para. 27.14].
GTG-N is a nowcast updated every 15 minutes, from 100 ft MSL to FL500 [1, para. 25.6].
Both are expressed as EDR, the ICAO standard for automated turbulence reports [1, paras. 24.5.4 and 25.6].
GTG is more accurate in daylight and busy airspace, where there are more reports [1, para. 27.14].
AIRMET Tango covers moderate turbulence; SIGMETs cover severe turbulence outside thunderstorms [1, para. 3.4.2.9].
A cumulonimbus always implies severe turbulence [1, para. 3.4.2.9].
Intensity runs light, moderate, severe, extreme, by aircraft reaction [3, para. 7-1-21].

Hover, focus, or tap any dotted term for a definition and its official source.

The Handbook puts it simply: "Turbulence is caused by convective currents (called convective turbulence), obstructions in the wind flow (called mechanical turbulence), and wind shear." [1, para. 19.2] No single product covers all three. This page explains the two automated NWS turbulence products, GTG and GTG-N, the EDR scale they use, the official intensity terms, and the advisories that fill the gaps. The Aviation Weather Center's GTG page was not available when this page was written, so the product descriptions come from the FAA Aviation Weather Handbook, with the AIM and FAA Advisory Circular 120-88A [1][2][3].

Which products carry turbulence information?

The Handbook's Table 3-12 lists them. The main ones [1, para. 3.4.2.9]:

Product	Kind	What it says about turbulence
PIREP	Observation	Location, altitude, aircraft type, and intensity judged by the pilot; severe or extreme makes it urgent [1, para. 3.4.2.9]
Radar and satellite	Observation	"Convective weather on radar could indicate potential areas of severe turbulence." "CB always implies severe turbulence." [1, para. 3.4.2.9]
GTG-N	Automated nowcast	Current turbulence, updated every 15 minutes [1, para. 25.6]
GTG	Automated forecast	Clear air and mountain wave turbulence out to 18 hours [1, para. 27.14]
AIRMET Tango	Advisory	"AIRMET Tango depicts areas of active or expected moderate turbulence." It is split into high and low at 18,000 ft [1, para. 3.4.2.9]
SIGMET	Advisory	Severe turbulence not associated with thunderstorms [1, para. 3.4.2.9]
Convective SIGMET	Advisory	"Possible severe turbulence is implied within the convective SIGMET area." [1, para. 3.4.2.9]
CWA	Advisory	Moderate or greater turbulence not already covered by an AIRMET or SIGMET [1, para. 3.4.2.9]

A TAF can hint at low-level mechanical turbulence too, when it forecasts strong, gusty surface winds [1, para. 3.4.2.9]. The advisory rules are in the advisories guide.

What is Graphical Turbulence Guidance (GTG)?

"The NWS produces a turbulence product that is derived from airborne turbulence observations and NWS model data with no forecaster modifications. This product is GTG." [1, para. 27.14]

How GTG builds a forecast

"GTG computes the results from more than 10 turbulence algorithms", compares each with turbulence reports from PIREPs and AMDAR automated aircraft data, and weights the algorithms by how well they match. The result is a single forecast [1, para. 27.14]. That design has a consequence the Handbook spells out: "This means the accuracy of GTG improves during daylight hours and where there is more traffic making PIREPs and sending of AMDAR data." [1, para. 27.14] At night and in remote areas, fewer reports means less to calibrate against.

When and where GTG is valid

"GTG produces its forecasts every hour." "Currently, GTG has separate forecasts for each hour through the first three hours, followed by forecasts at three-hour intervals through 18 hours." Forecasts cover select altitudes from 1,000 ft MSL through FL450 [1, para. 27.14].

Why GTG asks how big your airplane is

Turbulence feels different in different airplanes. The Handbook notes that "It is important to note that the effect of turbulence varies based on the size of the aircraft." [1, para. 19.1] So GTG forecasts are scaled to three ICAO weight classes [1, para. 27.14]:

GTG weight class	Aircraft weight (lb)	Examples
Light	Less than 15,500	Most piston singles and twins
Medium	15,500 to 300,000	Regional and narrow-body jets
Heavy	More than 300,000	Wide-body jets

The example column is ours, for orientation; check your airplane's weight. The same air can feel much rougher in a light single than in a wide-body.

What GTG shows, and what it leaves out

GTG provides three depictions: clear air turbulence (CAT), mountain wave turbulence (MWT), and "Combined Turbulence (the Combined GTG product depicts the higher of CAT values and MWT values at any given point)." [1, para. 27.14] The limit matters as much as the product: "GTG does not specifically predict turbulence associated with convective clouds or small-scale local terrain features, but it does predict turbulence associated with upper-level clear and mountain wave sources." [1, para. 27.14] A clear GTG chart says nothing about the thunderstorm on your route or the rotor behind the ridge.

Source conflict, noted: FAA Advisory Circular 120-88A, dated 2006, describes an early GTG that covered only altitudes above FL200 at 3-hour intervals out to 12 hours [2, app. 3]. The 2026 Aviation Weather Handbook describes today's product: 1,000 ft MSL through FL450, out to 18 hours [1, para. 27.14]. This page uses the Handbook.

What is GTG-N, the turbulence nowcast?

"The GTG Nowcast (GTG-N) product has been developed as a tactical aid for aviation." It shows the current turbulent state of the atmosphere over the contiguous U.S. in near real time, updating every 15 minutes [1, para. 25.6].

It starts from the most recent one-hour GTG forecast. "Recent observations of turbulence are then used to update the GTG forecast and create a blended nowcast (expressed as EDR)." The inputs are PIREPs, automated in situ EDR reports from aircraft, and EDR estimated from NEXRAD radar [1, para. 25.6]. GTG-N is available at 100 ft MSL, 1,000 ft MSL, and then every 1,000 ft up to FL500 [1, para. 25.6].

So GTG-N is a forecast corrected by observations, not an observation itself. Where no aircraft has reported recently, it leans on the forecast.

What is EDR?

Both products speak in eddy dissipation rate. "EDR is the ICAO standard dimension for automated turbulence reporting." "EDR is a state of the atmosphere measure rather than a state of the aircraft measure, and is, therefore, independent of aircraft type." [1, para. 24.5.4] The FAA's turbulence advisory circular describes the same idea: "EDR software utilizes inputs from standard aircraft performance systems to generate an aircraft independent turbulence metric." "ICAO has adopted EDR as the international standard for automated turbulence reporting." [2, app. 3]

Because EDR describes the air, not the ride, it has to be translated into light, moderate, or severe for a given airplane. That is why GTG is scaled by weight class [1, para. 27.14]. Read the color legend on the display you use; this page doesn't give EDR thresholds because none of the FAA documents used here defines them.

How is turbulence intensity defined?

By aircraft reaction, on the AIM's four-step scale [3, para. 7-1-21]:

Intensity	Aircraft reaction, AIM wording
Light	"Turbulence that momentarily causes slight, erratic changes in altitude and/or attitude (pitch, roll, yaw)."
Moderate	Like light but stronger. "Changes in altitude and/or attitude occur but the aircraft remains in positive control at all times."
Severe	"Turbulence that causes large, abrupt changes in altitude and/or attitude. It usually causes large variations in indicated airspeed. Aircraft may be momentarily out of control."
Extreme	"Turbulence in which the aircraft is violently tossed about and is practically impossible to control. It may cause structural damage."

Reports add duration: occasional is less than 1/3 of the time, intermittent 1/3 to 2/3, and continuous more than 2/3 [3, para. 7-1-21]. The full AIM table, including what happens inside the cabin and how chop is reported, is in the PIREP guide.

Clear air turbulence

High-level turbulence, normally above 15,000 ft and not associated with cumuliform clouds, is reported as CAT [3, para. 7-1-21]. The AIM says "CAT has become a very serious operational factor to flight operations at all levels and especially to jet traffic flying in excess of 15,000 feet." Pilots who meet it are urgently asked to report time, location, and intensity [3, para. 7-1-23].

What about thunderstorm and terrain turbulence?

These are exactly the types GTG leaves out, so other sources carry them.

Thunderstorms. "CB always implies severe turbulence." [1, para. 3.4.2.9] "ATC radar is not able to detect turbulence." "Turbulence should be expected to occur near convective activity, even in clear air." [3, para. 7-1-12] The Handbook adds that "hazardous turbulence may extend to as much as 20 mi from the echo edge" [1, para. 22.8.1]. See the radar guide.
Mountains. "Mountain waves are a form of mechanical turbulence that develop above and downwind of mountains." [1, para. 19.2.2.1] GTG forecasts mountain wave turbulence, but not small-scale terrain effects [1, para. 27.14]. Strong winds across a ridge in the winds aloft forecast are a clue.
Low-level mechanical turbulence. Strong, gusty surface winds in a TAF or METAR imply it near the ground [1, para. 3.4.2.9].

Where are the official turbulence product descriptions?

Official turbulence product descriptions

Links checked September 29, 2026: all returned HTTP 200.

Where do turbulence forecasts mislead pilots?

Wrong weight class. A chart set for medium or heavy aircraft will understate what a light airplane feels [1, para. 27.14].
Missing convection. GTG does not forecast thunderstorm turbulence [1, para. 27.14].
Thin data at night. GTG is calibrated against reports, so accuracy drops when there are fewer of them [1, para. 27.14].
Reports are relative. A PIREP of moderate from a large jet means something different from moderate in a light single; check the aircraft type (PIREP guide).

How do you use turbulence forecasts in a go/no-go decision?

The decision is yours as pilot in command. A few habits:

Start with advisories. SIGMETs, Convective SIGMETs, and AIRMET Tango first, then GTG for detail by altitude and time [1, para. 3.4.2.9].
Check the weight class and altitude. Read GTG at your cruise altitude, for your class [1, para. 27.14].
Confirm with PIREPs. Recent reports from similar aircraft near your altitude are the best check. Give one back.
Plan an out. A different altitude or route. Record it in a FRAT [4, ch. 3].

Where do turbulence forecasts fit in a disciplined decision?

PlaneWX is decision support for general aviation pilots, built around one idea: "Fly like it's your job." Treat the weather decision the way a professional crew would, with the same process every time. That process is a loop: Brief, then FRAT, then Fly or Stay, then Debrief, with a Mentor if you want one. Turbulence products feed the Brief. Here's how PlaneWX handles them, as described in the help center [5]:

Brief: which turbulence data. PlaneWX uses the "GTGN nowcast (observation-fused EDR, updated every 15 minutes)" for imminent departures and the DAFS GTG forecast out to 18 hours, with model wind shear analysis for context and beyond 18 hours (Turbulence Analysis).
Brief: reports weighed by aircraft. Turbulence PIREPs are normalized by weight class: reports from light aircraft under 15,500 lb are not adjusted, and reports from heavier aircraft are stepped up (Turbulence Analysis).
Brief: confirmed beats modeled. Corroborated PIREPs or active SIGMETs beyond your hard limit fail the pre-flight check and set the WX Score to 0%, because "PIREPs and SIGMETs are confirmed reports, not model estimates." A GTG-N exceedance alone gives a caution and a score reduction (Turbulence Analysis).
FRAT. The flight risk assessment opens within 4 hours of departure, and your own ratings drive it (FRAT).
Fly or Stay. "PlaneWX never recommends GO or NO-GO. You make the call as PIC." (The Risk Loop)
Debrief. If the ride differed from the forecast, file the PIREP. Self Debrief is a PlaneWX Labs feature for Pro Plus (The Risk Loop).

The help center is plain about the limits: "PlaneWX is not a substitute for a complete, independent pre-flight weather briefing. Pull one from a source you already trust before you fly." (The Risk Loop)

See the turbulence picture along your next route in a PlaneWX briefing, or read how PlaneWX analyzes turbulence. Related: PlaneWX research on turbulence safety.

Frequently asked questions

What is GTG?

Graphical Turbulence Guidance, the NWS automated turbulence forecast. It blends more than 10 turbulence algorithms, weighted by how well each matches PIREPs and automated aircraft reports, with no forecaster changes [1, para. 27.14].

What is the difference between GTG and GTG-N?

GTG is a forecast, issued every hour out to 18 hours. GTG-N is a nowcast of current turbulence over the contiguous U.S., updated every 15 minutes by blending the latest one-hour GTG forecast with recent turbulence observations [1, paras. 25.6 and 27.14].

Does GTG forecast thunderstorm turbulence?

No. "GTG does not specifically predict turbulence associated with convective clouds or small-scale local terrain features, but it does predict turbulence associated with upper-level clear and mountain wave sources." [1, para. 27.14]

What is EDR?

Eddy dissipation rate. "EDR is the ICAO standard dimension for automated turbulence reporting." It measures the atmosphere, not the aircraft, so it does not depend on aircraft type [1, para. 24.5.4].

Which GTG weight class should a light airplane use?

Light, under 15,500 lb. GTG forecasts are scaled to three ICAO weight classes: light below 15,500 lb, heavy above 300,000 lb, and medium in between [1, para. 27.14].

Can ATC see turbulence on radar?

No. "ATC radar is not able to detect turbulence." Turbulence generally increases with precipitation intensity, and it should be expected near convective activity, even in clear air [3, para. 7-1-12].

How far should I stay from thunderstorms?

The AIM says operation within 20 miles of thunderstorms should be approached with great caution, and to avoid by at least 20 miles any thunderstorm identified as severe or giving an intense radar echo [3, paras. 7-1-12 and 7-1-27].

What is the official turbulence intensity scale?

Light, moderate, severe, and extreme, defined by aircraft reaction, with duration reported as occasional, intermittent, or continuous [3, para. 7-1-21]. The full table is in the PIREP guide.

How does PlaneWX use GTG?

The help center says PlaneWX uses the GTG-N nowcast for imminent departures and the DAFS GTG forecast out to 18 hours, adds model wind shear analysis, and normalizes turbulence PIREPs by aircraft weight. PlaneWX never recommends GO or NO-GO; you make the call as PIC [5].

Glossary

Every term below links to the FAA, NWS, or NOAA document that defines it. The same definitions appear when you hover, focus, or tap a dotted term on this page.

AIRMET Tango: The AIRMET series for moderate turbulence, strong sustained surface winds, and non-convective low-level wind shear. Source: FAA Aviation Weather Handbook, 26.3.1.2
AMDAR (Aircraft Meteorological Data Relay): The system that sends automated weather and turbulence reports from commercial aircraft sensors to the ground. Source: FAA Aviation Weather Handbook, 24.5.4
CAT (Clear air turbulence): High-level turbulence, normally above 15,000 feet, that is not associated with cumuliform clouds, including thunderstorms. Source: AIM, 7-1-21
Convective SIGMET: The SIGMET issued for thunderstorms over the contiguous U.S. It implies severe or greater turbulence, severe icing, and low-level wind shear. Source: FAA Aviation Weather Handbook, 26.2.4.2
CWA (Center Weather Advisory): A short-term advisory from a Center Weather Service Unit for weather that meets or approaches AIRMET or SIGMET criteria, valid for up to 2 hours. Source: FAA Aviation Weather Handbook, 26.4
EDR (Eddy dissipation rate): The ICAO standard measure for automated turbulence reports. It describes the atmosphere rather than one aircraft, so it does not depend on aircraft type. Source: FAA Aviation Weather Handbook, 24.5.4
FRAT (Flight Risk Assessment Tool): A form or checklist for recording flight hazards and the risk they add up to before you fly. Source: FAA Risk Management Handbook, Chapter 3, Using a Flight Risk Assessment Tool (FRAT)
GTG (Graphical Turbulence Guidance): The NWS automated turbulence forecast for clear air and mountain wave turbulence, issued hourly out to 18 hours and scaled to aircraft weight class. Source: FAA Aviation Weather Handbook, 27.14
GTG-N (Graphical Turbulence Guidance Nowcast): A near real-time turbulence nowcast for the contiguous U.S., updated every 15 minutes by blending the latest GTG forecast with recent turbulence observations. Source: FAA Aviation Weather Handbook, 25.6
NEXRAD (Next Generation Weather Radar, the WSR-88D): The network of 160 NWS, FAA, and military Doppler weather radars whose data feeds the radar images pilots see. Source: FAA Aviation Weather Handbook, 24.6.1
PIREP (Pilot Weather Report): A report of weather a pilot actually encountered in flight, shared to help other pilots and forecasters. Source: FAA Aviation Weather Handbook, 24.5.1
SIGMET (Significant Meteorological Information): An unscheduled warning of en route weather that may affect the safety of aircraft operations, such as severe icing, severe turbulence, widespread dust storms or sandstorms, and volcanic ash. Source: FAA Aviation Weather Handbook, 26.2

This page explains published FAA and NWS guidance. Always get a current briefing before you fly.

References

FAA-H-8083-28B, "Aviation Weather Handbook." Federal Aviation Administration, Flight Standards Service. April 2, 2026. Paragraphs cited: 3.4.2.9 (Table 3-12), 19.1, 19.2, 19.2.2.1, 22.8.1, 24.5.4, 25.6, 27.14. https://www.faa.gov/regulationspolicies/handbooksmanuals/aviation/faa-h-8083-28b-aviation-weather-handbook. PDF: https://www.faa.gov/sites/faa.gov/files/FAA-H-8083-28B.pdf
AC 120-88A, "Preventing Injuries Caused by Turbulence." Federal Aviation Administration. January 19, 2006. Appendix 3. https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC120-88A.pdf
"7-1-12. ATC Inflight Weather Avoidance Assistance," "7-1-21. PIREPs Relating to Turbulence," "7-1-23. Clear Air Turbulence (CAT) PIREPs," and "7-1-27. Thunderstorm Flying." Aeronautical Information Manual (AIM), Chapter 7, Section 1. Federal Aviation Administration. Effective July 9, 2026 (Change 3). https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap7_section_1.html
FAA-H-8083-2A, "Risk Management Handbook." Federal Aviation Administration. 2022. Chapter 3, "Using a Flight Risk Assessment Tool (FRAT)." https://www.faa.gov/regulationspolicies/handbooksmanuals/risk-management-handbook-faa-h-8083-2a
PlaneWX Help Center: "Turbulence Analysis," "FRAT," "The Risk Loop." PlaneWX. Accessed September 29, 2026. Turbulence Analysis · FRAT · The Risk Loop