Getting Into The Forecaster’s Head

With ForeFlight 7.5 you’ll have the ability to peer into the minds of forecasters. Yeah, I know… scary thought! No, we haven’t developed a method for mental telepathy within the app; but, we now provide access to the forecaster’s thinking about the latest set of Terminal Aerodrome Forecasts (TAFs) they recently issued. These are referred to as Area Forecast Discussions or AFDs. Let’s take a look at how these can be used in your routine flight planning.

Let’s say you are planning to fly into Charlotte Douglas International Airport (KCLT) arriving in the early afternoon around 1800 UTC and the latest terminal forecast issued at 1140 UTC shows good visibility (P6SM) with showers in the vicinity (VCSH) and a broken ceiling at 7,000 feet (BKN070) at the time of your proposed arrival. Does this worry you even a little bit? After all, high-base rain showers in the vicinity of the airport appears to be fairly harmless even for a pilot flying VFR? Actually, this should concern you – this may just be a forecast for thunder.

CLT-Terminal-Area

The red circle annotated here on the Charlotte TAC represents the 5 statute mile radius of the Charlotte Douglas Airport (KCLT) terminal area. This is the tiny region that forecasters consider when issuing a Terminal Aerodrome Forecast (TAF).

Just because you don’t see a forecast for TS, TSRA or VCTS in a TAF, doesn’t that mean you won’t see thunderstorms arriving or departing that airport. What it could mean is that the forecaster wasn’t confident enough at the time he/she issued the forecast that a thunderstorm would develop within or roll through the region referred to as the terminal area. The terminal area is the region of airspace within a 5 statute mile radius from the center of the airport’s runway complex like the one shown above for the Charlotte Douglas International Airport (KCLT). So it is common for meteorologists to use showers in the vicinity (VCSH) or rain showers (SHRA) as a placeholder for thunder when forecaster confidence is low.

Here’s the problem

The forecaster doesn’t have an obvious way to quantify his/her uncertainty in the actual body of the coded TAF. Quantifying uncertainty is paramount when constructing any forecast (especially one for thunderstorms) and is usually done with a probabilistic approach – you know, a chance of this or a chance of that.

What about the PROB group that you may have seen in a TAF? Sure, that would work, but NWS directives state that a PROB30 group can’t appear within the first nine hours of the terminal forecast. By the way, the NWS only uses PROB30 groups; although you may see PROB40 in TAFs when flying to other countries. So back to the issue – how does a pilot know that showers in the vicinity is a placeholder for thunder in the TAF issued for Charlotte Douglas International Airport?

AFDs to the rescue

First, AFD doesn’t stand for Airport/Facility Directory as you may have thought. It’s called an Area Forecast Discussion. Second, it’s not a discussion about the aviation Area Forecast (FA) issued by meteorologists at the Aviation Weather Center. Are you thoroughly confused yet? The AFD is one of the most commonly accessed products on NWS Web sites, however, very few pilots have even heard of them. Now they are available for you to read beginning to end in the ForeFlight Mobile app!

County Warning Areas

A map of the County Warning Areas (CWAs) across the United States. There is an Area Forecast Discussion (AFD) generated for each one of these CWAs.

The AFD is a discussion that is written by the same forecasters that issue the TAFs. Every NWS local Weather Forecast Office (WFO) throughout the United States issues terminal forecasts for airports that appear within their County Warning Area (CWA), hence the term Area Forecast Discussion. After TAF issuance, meteorologists are required to update the AFD with a plain english discussion explaining their thoughts behind the forecast which allows them a plethora of ways to quantify their uncertainty. AFDs were originally designed as technical discussions to enhance collaboration among NWS forecast offices and to convey uncertainty to a specialized audience. So the language can be quite technical at times, but still highly useful to pilots. Let’s get back to your flight into Charlotte.

The GSP AFD has some clues

For example, the AFD associated with this TAF for the Charlotte Douglas Airport is written by a forecaster located at the Greenville-Spartanburg WFO (GSP) in Greer, South Carolina. Here’s the pertinent part of the discussion that morning:

AVIATION /16Z TUESDAY THROUGH SATURDAY/…

AT KCLT…LITTLE CHANGE FROM 06 UTC PACKAGE AS A WEST WIND LESS THAN 8 KTS UNDER MOSTLY CLEAR SKIES WILL CONTINUE THROUGH MID-MORNING. EXPECT INCREASING WSW WINDS WITH LOW AMPLITUDE GUST POTENTIAL BY MIDDAY AND PERHAPS PERIODS OF VFR CEILINGS THROUGH THE AFTERNOON. SCATTERED SHOWERS AND A PERHAPS A THUNDERSTORM…ARE EXPECTED ACROSS THE NORTH CAROLINA PIEDMONT FROM THE AFTERNOON UNTIL EARLY EVENING AND WILL CARRY VCSH FOR NOW TO COVER THAT THREAT. DEEP CONVECTIVE ACTIVITY WILL DIMINISH BY MID-EVENING WHEN A WIND SHIFT TO NORTHWEST IS EXPECTED.

As stated in this AFD text that is highlighted above, the forecaster opted to use showers in the vicinity (VCSH) to cover the threat for thunder in the North Carolina Piedmont region where KCLT is located. Most pilots don’t realize or appreciate that showery precipitation is actually a convective process. So forecasters will often use showers as a placeholder when confidence of thunder is low. This is not to say that every forecast for showers is used in this way, but that is a common way the forecaster quantifies his/her uncertainty for convective events such as this.

For whatever reason, the forecaster wasn’t quite confident enough to impart a little meteorological risk and add thunderstorms to the Charlotte TAF. This is in part due to the relatively small size of the terminal area. If the thunderstorms in the area are anticipated to be of a scattered nature (as it was on this day), they will often omit a forecast for thunder until they are more certain thunderstorms will indeed impact the terminal area. In some situations they may use showers to hint that convection will be in the area without adding TSRA or VCTS to the forecast. As the convective weather event evolves and certainty increases, they will issue an amended forecast to add thunder. But these details are not part of the official forecast. For better or for worse, they are buried in the AFD. The AFD is the place where the forecaster can freely quantify his/her uncertainty and provide some background on why the forecast is constructed the way it is.

Moreover, meteorologists at the local weather forecast offices that issue forecasts for high impact terminal areas such as Charlotte Douglas have a fair amount of outside pressure from the airlines to avoid adding thunder to the forecast unless convection is fairly certain. A forecast for thunder at the proposed time of arrival means the airlines must file an alternate and carry extra fuel to get to that alternate.

So what actually occurred at Charlotte Douglas?

Did thunder ever affect the Charlotte terminal area? Yes, at 1813 UTC the observation (METAR) included a report for a thunderstorm at the airport as shown below.

KCLT 271813Z 07003KT 10SM TS SCT040CB BKN090 BKN200 16/09 A2956
RMK AO2 TSB13 OCNL LTGIC TS SE-SW-W MOVG E CB NW-N MOVG E

But, it wasn’t until 1739 UTC (a mere 34 minutes earlier) that the forecaster amended the TAF to include a forecast for light rain and thunder as shown below.  Some pilots might opine that the TAF issued at 1140 UTC was a bad forecast. However, given the scattered nature of the convection on this day (read uncertainty) the placeholder of showers in the vicinity was the method used to indicate the risk of thunder. The AFD was the place the forecaster documented this important piece of information.

KCLT 271739Z 2718/2818 26008G18KT 6SM -TSRA BR BKN045 OVC070CB
TEMPO 2718/2720 25010G20KT 5SM -TSRA BR SCT030 OVC050CB…

The AFD format

The raw AFD doesn’t have a rigid syntactical or semantic format that forecasters must follow. Moreover, that format may differ from one forecast office to the next. That’s both good and bad. At ForeFlight we do make an attempt to visually separate the discussion into sections with a header where it is possible. Although you may find that some WFOs do a better job than others sticking to a common format as described below; so don’t count on perfection with the AFDs.

AFD Synopsis

Most Area Forecast Discussions (AFDs) will contain a synopsis section followed by a near-, short-, and long-term discussion. Simply scroll the window down with your finger or stylus to see the rest.

Each AFD will typically start out with a SYNOPSIS section (as shown above) followed by a NEAR TERM, SHORT TERM and LONG TERM discussion. This is the accepted format for the NWS Eastern Region. In other regions you may just see one big DISCUSSION section. While not specific to aviation, these sections are important to read and often may describe the “big picture” and point out many clues and trends as to what adverse weather might occur over the next several hours or even several days. Of the most interest to pilots, every AFD will also include an AVIATION section like the one shown below. This is the section where the forecaster discusses the TAFs and aviation-specific concerns. Lastly, in some parts of the country you may find a separate section that discusses fire dangers and marine weather.

AFD Aviation

Every AFD should have an aviation section. The AFD is automatically scrolled to this section when first viewed. Also notice that key words or phrases may be highlighted in red to point out the discussion of various adverse weather elements.

While most of the sections in the AFD are word-wrapped, you may see some tabular sections like the confidence table shown below. In order to preserve the columnar format within this section, you can scroll these sections left and right with your finger or stylus (notice the horizontal scroll bar below this table).

AFD Tabular

Some sections in the Area Forecast Discussion (AFD) are tabular. In these cases, the section can be scrolled to the right to see the remaining part of the table.

Finding the AFD in ForeFlight

The AFD is available to all ForeFlight subscribers and to locate it in the app is as simple as finding a METAR or TAF. On the Map, bring up any airport-specific layer such as Flight Category and tap on the airport marker. Next, tap the Forecast tab at the bottom of the pop-over window then tap on the new Discussion button at the top to reveal the AFD for that airport’s CWA as shown below. The Discussion button will be located to the right of the MOS button.

AFD Location

The Area Forecast Discussion (AFD) is located under the Forecast tab on the station popover right next to the MOS button.

You can also view AFDs in the Airports view. With the airport of interest displayed, tap on the Weather tab, then tap on Forecast Discussion as shown below. However, be careful not to confuse this with the Airport/Facility Directory (A/FD) tab.

AFD Airports view

The Area Forecast Discussion (AFD) can be shown within the Airports view similar to the way METARs, TAFs and MOS are displayed.

The Fine Print

When tapping on the Discussion button in the pop-over window, the AFD is auto-scrolled to the Aviation section. From there you can scroll up or down to read the rest of the forecast discussion. Similarly in the Airports view, the Aviation section is also displayed first by tapping on Forecast Discussion under the Weather tab. Tapping on Forecast Discussion again, will position it to the beginning of the discussion text.

While most of the discussion is in plain english, there will be times where abbreviations and acronyms will rear their ugly head. We’ve made an honest attempt to decode most (but not all) of these within the text. Moreover, you will see some words and phrases highlighted in red. Hopefully these will grab your attention since they sometimes point out discussion that includes more extreme adverse weather.

Mind the limitations

AFDs are only available for airports within the United States (including Hawaii and Alaska). So selecting any airport within the U.S. should result in retrieving the latest AFD based on the CWA that airport is located within. Consequently, airports outside of the U.S. won’t have a Discussion button on the pop-over or under the weather tab on the Airports view. Occasionally, the latest AFD may not be available and you’ll see a “No forecast discussion” response. This is a very rare occurrence, but it may happen from time to time.

While some forecasters put a fair amount of time and detail describing their thoughts, not all AFDs will have details you might be hoping to learn. The AFD isn’t their highest priority; when the weather is busy the AFDs will often get the short end of the stick. That same forecaster may have to help with radar and issuing severe thunderstorm and tornado warnings on a busy convective day, for example.

In the end, expect the AFDs to provide a complementary product to the TAFs. If you are not reading the AFDs, you are only getting half the story.

ForeFlight Logbook, Area Forecast Discussions with 7.5

We are thrilled to deliver ForeFlight Logbook in our final release of the year. In addition, insightful Area Forecast Discussions are now built-in to airport weather views.

Simplicity, Utility, and Security with ForeFlight Logbook

Logbook is seamlessly integrated into the ForeFlight app, making it easy for pilots to manually and automatically log flights, track hours, review currency, record certificates and ratings, receive electronic instructor endorsements, and generate experience reports. In addition, your Logbook data is automatically and securely stored in the ForeFlight Cloud. ForeFlight’s servers regularly backup the logbook when changes or additions are made, delivering a new level of security and assurance for digital pilot logbook data. ForeFlight’s Sync platform seamlessly synchronizes your logbook information across all of the devices on your account.

Logbook is available as part of our new Basic Plus and Pro Plus plans or as an add-on to your existing plan, as well as an optional add-on to Business Pro multi-pilot plans. Learn more about Logbook at foreflight.com/logbook.

Get the Whole Weather Story with Area Forecast Discussions

Area Forecast Discussion in Maps viewAs Scott Dennstaedt says in his blog article on the topic, with ForeFlight 7.5 “you’ll have the ability to peer into the minds of forecasters.” Well, close. You can now access Area Forecast Discussions (AFDs) in ForeFlight.

Area Forecast Discussions are now provided for all US airports with their associated TAFs. These are issued by forecasters at the National Weather Service and provide important insights into forecast conditions, acting as a complement and explanation for recently issued TAFs.

The AFDs can be found in ForeFlight by tapping on a station in the Maps view, then tap Forecast in the pop-over. Also in the Airport view, tap the Weather tab then Forecast Discussion.

Check out Scott’s article where he walks through how AFDs can be routinely used in your flight planning. Do you know the size of the terminal area that is considered when a forecaster issues a TAF? Read Getting Into The Forecaster’s Head to find out.

New Subscription Plans Bring Added Features and Value

Coupled with the introduction of Logbook, we are also announcing new subscription plans for individual pilots that are designed to give you even more value from your ForeFlight experience. Logbook is an essential part of your flight bag and so we made it a standard feature in both of the new plans.

The new Basic Plus plan includes everything in the current Basic plan plus Logbook and Weight & Balance for $99.99/year.

The new Pro Plus plan includes everything in the current Pro plan plus Logbook and Synthetic Vision for $199.99/year.

If you are pleased with the plan you have now, you can still purchase or renew the existing Basic and Pro plans. You can manage this by logging in to foreflight.com/manage with your ForeFlight app credentials or by using our build your own plan link on foreflight.com/pricing.

For more details about the new plans, visit foreflight.com/pricing.

For Business customers with multi-pilot accounts, the Business Pro plan details can be viewed here.

New Firmware Update Available for Stratus 2 Devices

Appareo recently released a new firmware update for Stratus 2 devices, adding some features that were first introduced with the Stratus 2S. To update your Stratus 2:

  1. Connect to the Stratus Wi-Fi network.
  2. Navigate to More > Devices > Stratus inside ForeFlight.
  3. Tap the “Tap to Update” button next to the current firmware version.

This update adds a new item to the Settings section of the Devices > Stratus view: Wi-Fi Settings. Tap on the item to see the new settings.

Photo Dec 01, 3 59 07 PM

Disabling SSID Broadcast hides your network’s name from devices trying to connect to it, so the only way someone can access the network is if they already know its name. Another new setting is the option to enable WPA2 Security, which allows you to set a passcode on the network.

These settings make it harder for someone else to access your Stratus’ Wi-Fi network, though most pilots will probably not need this level of security. If you set a passcode but then forget it, you can perform a factory reset of the device by holding down the power button for 30 seconds. This will return the Wi-Fi Settings to their default states. Be warned, however, that a factory reset will also delete any Stratus logs saved on the device.

ForeFlight Web Moves to Open Beta

ForeFlight Web is now in open Beta, meaning that anyone with an active ForeFlight subscription can access it. Just go to plan.foreflight.com and sign in using your ForeFlight username and password.

ForeFlight Web

Plan a flight or view weather and airport information all from your web browser. Routes are synced to ForeFlight Mobile on all your devices, allowing you to pick up at the airport right where you left off at home.

As a Beta program, we’re continually refining and adding new features to ForeFlight Web, and we welcome any feedback you have about how it can be improved.

Learn more at foreflight.com/web.

ForeFlight is Ready for iPad Pro

Apple shipped the new iPad Pro this week and our dev team is already logging time with it in the cockpit. So far we are impressed with its performance. We also released ForeFlight 7.4 this week which is compatible with the new hardware.

ipads

We designed the 7.4 release to take advantage of the expanded screen real estate and display more information at once, including two more instruments in the Instrument Panel and expanded sections in the Weight & Balance view. Apple’s new A9X chip also provides incredible processing speed and graphics performance, making your flight planning more immersive than ever.

Flight testing with iPad Pro

Flight testing with the iPad Pro!

If you can find room for it in your cockpit, you can view more of a chart at once, and going split-screen with Synthetic Vision still provides the same amount of chart space as an iPad Air. The Pro in landscape orientation is equivalent in screen size to two iPad Airs side-by-side! And despite the large screen, we’ve seen great battery performance out of it so far. We are looking forward to all the new possibilities on this platform.

ForeFlight Partners with Gogo on Inflight Connectivity

We are excited to announce our partnership with Gogo to make ForeFlight Mobile available to customers using Gogo’s ATG 1000 inflight connectivity system beginning in December 2015.gogo-logo

ForeFlight customers on aircraft equipped with the ATG 1000 can take advantage of the app’s full range of real-time information inflight, including up to the minute weather, Flight Notifications, NOTAMs and TFRs, as well as Cockpit Sharing – a feature pilots can use to wirelessly share route information with one another and with passengers’ iPads and iPhones.

Tyson Weihs, ForeFlight co-founder and CEO, shared: “Internet connectivity with the ATG 1000 is yet another example of our commitment to give our customers every possibility to enhance their in-flight experience with ForeFlight Mobile. In addition, many business passengers are also pilots or they may have an active interest in aviation. ForeFlight Mobile allows them to see the weather and route information that the pilots up front are seeing.”

New Graphical Preflight Briefing, Track Log and Weather Upgrades in ForeFlight 7.4

For years, pilots have endured a cryptic, wall-of-text preflight briefing. With ForeFlight Mobile 7.4, we are thrilled to introduce ForeFlight Briefing—a graphical, translated, interactive briefing that helps you better visualize weather and related flight information along your proposed route. This release also delivers an enhanced AIR/SIGMETs map layer and new Track Log capabilities that allow you to automatically record your flights.

You Can Brief Clearly Now With ForeFlight Briefing

ForeFlight Briefing is a standard briefing with content derived from approved government sources. It includes all the elements of a standard preflight briefing prescribed by the FAA—adverse conditions, synopsis, current conditions, enroute and destination forecasts, NOTAMs, and more—delivered in a visually elegant design for enhanced readability. With this next generation briefing format, we believe you will enjoy and get more from the preflight briefing.

ForeFlight Briefing is seamlessly integrated into the ForeFlight Mobile app and is presented in clearly organized sections, making it simple to tap through each element of the briefing in a logical sequence. Translated and raw text options are available, as well as full-color graphics, which help you better understand and consume briefing information.

ForeFlight Briefing organized into logical sections

Some helpful aspects of the new briefing include color-coding and notations to indicate if an advisory will be active or inactive during or near your passing time:

ForeFlight Briefing with active and inactive AIRMET alertAlso, colored dots used in conjunction with METARs and TAFs give you an at-a-glance view of current and forecast weather. In the screen shot above, green represents VFR, blue is marginal VFR, red is IFR, and magenta is low IFR.

In the TAF view, color-coding is again used to indicate the forecast flight category. Based on your planned departure time and aircraft profile, your passing time at each station is automatically calculated and plotted on the TAF:

ForeFlight Briefing on the iPad and iPhoneThe briefing is mobile and portable—once the briefing is retrieved, you do not need an Internet connection to access it again on the go. In addition, after you file your flight plan you can click the link in your confirmation email to view the briefing on any web browser.

In addition, ForeFlight Briefings are timestamped and stored on your iPad and iPhone, and in the ForeFlight cloud, to record that you obtained weather and pertinent NOTAMs in compliant manner with 14 CFR 91.103(a) preflight action.

ForeFlight Briefing is available to all customers with ForeFlight Mobile version 7.4 on both the iPad and iPhone. Customers with 7.4 installed will be automatically given the opportunity to use the new format the next time they brief a planned flight.

For more information visit foreflight.com/briefing/.

Global SIGMETs, New Graphical Center Weather Advisories

The refreshed AIR/SIGMET/CWAs Map layer now includes graphical Center Weather Advisories (CWAs) alongside AIRMETs and SIGMETs, giving you a better picture of current conditions. SIGMETs are also expanded to include global coverage.

Refreshed AIR/SIGMET/CWA map layer

A new interactive filter on this layer helps you single out adverse condition advisories based on type (icing, turbulence, IFR conditions, and thunderstorms), allowing you to declutter and get straight to the information you want to know:

AIR/SIGMET/CWA layer filter

Scott Dennstaedt, our in-house Weather Scientist, has written this blog post and this one to provide more insight on how to use these helpful weather resources in your everyday flight planning.

Capture Every Flight—Automatically

Have you ever been half-an-hour into a flight and realized you forgot to tap the Track Log record button? Now you don’t have to remember! With 7.4, we’ve made it easier than ever to record your flights.

Track Log shown in Google Earth.

Track Log shown in Google Earth.

Track Logs can automatically start recording when you take off and, after touchdown, automatically stop recording—ensuring that every flight is captured for your post-flight debrief. When you get back to Wi-Fi, Track Logs are also automatically uploaded to the ForeFlight cloud for safekeeping and for easy access from your other devices.

The Track Log includes your taxi time so you can have a complete record of your time in the cockpit — on and off the ground.

You can control the auto-record function in the app settings:
Track Log record settings

(Please note that Stratus Track Logs do not currently auto-upload.)

Apple iOS 9 Spotlight Search

ForeFlight Mobile 7.4 supports Spotlight Search, Apple’s smart search feature, which now displays relevant airport results from inside ForeFlight Mobile right on your device’s Home page.

ForeFlight and Apple Spotlight Search

To access Spotlight Search, swipe from left to right on the Home page of your iPad or iPhone. Begin typing an airport name, identifier, or city name and results from ForeFlight Mobile populate the search results list. Tap the desired airport search result and ForeFlight Mobile opens directly to that location in the Airports view. To continue searching, tap “Back to Search” in the upper left corner of the screen to return to the Spotlight Search view. Spotlight Search is available on iPhone 5 and up, all iPad Air models, and iPad Mini 2 and up.

App-Store-icon

ForeFlight Mobile 7.4 is a free update available on the App Store.

Weather On The Front Lines

If you surveyed a group of general aviation pilots, it would probably not surprise you to learn that Center Weather Advisories are not a weather source that pilots use very frequently when planning a flight. They have always been included within the ForeFlight Mobile app by tapping the Brief button under File & Brief. But this standard briefing only provides the advisory in raw text form—unless of course you are using the new and improved ForeFlight Briefing where it is also displayed graphically. In ForeFlight Mobile 7.4, Center Weather Advisories are now depicted graphically within the existing AIR/SIGMET layer on the Map view making them even more useful.

In-flight advisory

Center Weather Advisories, or CWAs, are the “front lines” of aviation weather in the U.S. for adverse weather such as low IFR conditions, thunderstorms, icing, and turbulence. While they smell a lot like AIRMETs and SIGMETs, they are more of an in-flight advisory about current conditions than they are a planning tool or forecast. Therefore, it’s critical to look for these while en route to your destination and just before you close the door to depart. Now is a good time to mention that CWAs are not part of the ADS-B broadcast so you will not receive them while connected to a Stratus.

Center centric

CWAs are issued by highly trained meteorologists at the Center Weather Service Units (CWSUs) located at the various Air Route Traffic Control Centers (ARTCCs) pictured below.

ARTCC Map

A map of the Air Route Traffic Control Center (ARTCC) boundaries in the U.S. Each ARTCC has a Center Weather Service Unit (CWSU) staffed by meteorologists that are responsible for issuing Center Weather Advisories (CWAs) for their respective ARTCC area.

CWAs are issued to warn pilots of the following in-flight weather hazards:

  • Conditions meeting or expecting to meet convective SIGMET criteria
  • Moderate or greater airframe icing
  • Moderate or greater turbulence
  • Heavy precipitation
  • Freezing precipitation
  • Conditions at or approaching Low IFR
  • Sustained surface winds/gusts > 30 knots
  • Non-convective low level wind shear below 2,000 feet AGL
  • Volcanic ash, dust storms, or sandstorms

Short lead time

Unlike their AIRMET counterpart, CWAs are not routinely issued and have no defined schedule. Moreover, they have a very short lead time since they are issued on an as-needed basis. So it’s not unusual to see a CWA issued at 20 minutes past the hour to describe adverse weather that has evolved very rapidly. Once issued, CWAs are valid for two hours or less. If conditions are anticipated to persist beyond two hours, it will be indicated in the last line of the CWA text. As mentioned earlier, CWAs are not as valuable of a preflight planning tool because of its short lead time and duration. They tend to pop up as adverse weather evolves or develops throughout the U.S. and along its coastal waters.

Complementary guidance to other advisories

Forecasters at the CWSUs have a fair amount of latitude when issuing a CWA. Conditions do not have to meet national in-flight advisory criteria in terms of intensity or areal coverage. For example, unlike convective SIGMETs, CWAs for convection can be issued before thunderstorms have formed. That is, they can describe a broad area of towering cumulus or showery precipitation that is trending toward an aviation hazard within the next two hours especially in regions that may affect flow into or out of busy airspace. Convective SIGMETs issued by forecasters at the Aviation Weather Center (AWC) are more of a NOWcast that warn pilots about active areas of thunderstorms that have already met specific hazard criteria.

A good example of its complementary nature is a CWA for low IFR conditions. An AIRMET for IFR conditions is primarily directed at pilots flying under visual flight rules (VFR). It describes an area that may experience a ceiling and/or visibility below VFR minimums. However, what if a portion of the AIRMET region is also plagued with persistent low IFR conditions? This would be critical information for all pilots including those flying under instrument flight rules (IFR). As shown below, given the number of stations reporting low IFR conditions (magenta markers) within the AIRMET region, the Denver CWSU issued a CWA for ceilings at or below 500 feet and visibility at or below 1/2 statute miles.

Low IFR CWA

This Center Weather Advisory (CWA) was issued for ceilings at or below 500 feet and visibilities at or below 1/2 statute mile that were occurring within an existing AIRMET for IFR conditions.

While CWAs can be issued at any time, they are generally coordinated with other agencies within NOAA to ensure meteorological consistency between products. This includes meteorologists at the AWC who are responsible for issuing the area forecast, AIRMETs, SIGMETs and convective SIGMETs. It’s pretty typical for the meteorologist at the CWSU to have a brief phone conversation with the appropriate meteorologist at the AWC before issuing a new CWA.

Finding CWAs in ForeFlight

The CWA layer can be displayed from the Map view in ForeFlight Mobile 7.4. Simply tap the Map mode button in the upper left and select AIR/SIGMET/CWAs from the menu as shown below:

CWA Menu

Center Weather Advisories (CWAs) can be selected from tapping the mode button and selecting AIR/SIGMET/CWAs from that menu.

Once the layer has been selected you will see CWAs depicted on the ForeFlight map view as cyan-colored polygons regardless of the hazard type. In most cases, these areas will be smaller in size than an AIRMET or SIGMET because of their complementary nature and short duration. To see the associated uncoded text of the CWA, simply tap on the polygon in the same way that you view the uncoded text for AIRMETs and SIGMETs. Be sure to always read the text of the CWA since it will have additional details about the flight conditions such as the altitudes affected and an indication of whether or not conditions are expected to improve or persist beyond the valid time.

Buttons

When AIR/SIGMET/CWAs are selected, the four buttons at the bottom of the Map allow you to filter advisories according to hazard type.

Lastly, given that CWAs are a complementary product to AIRMETs, SIGMETs and convective SIGMETs, with ForeFlight Mobile 7.4 you can overlay them with other advisories. Tapping on the buttons at the bottom labeled Ice, Turb, IFR and TS, will permit you to add or remove CWAs from the Map based on hazard type. In this example above, only IFR hazards are selected which includes AIRMETs for IFR conditions and mountain obscuration as well as a single CWA for low IFR conditions captured by the cyan-colored polygon. Any advisories for icing, turbulence and convection (if any) have been filtered from the Map.

VFR Arrival/Departure Routes Documents Available in Military Flight Bag

VFR Arrival/Departure Routes for Europe and Korea are now available to our Military Flight Bag customers. These documents include general and regional information as well as detailed procedures for many airports and heliports. Specific airport information was previously available in the Airport and Plates views, but now regional and supplemental information is available inside our Documents Catalog.

vfr-routes-catalog bezel

To download these new documents, tap the Catalog button inside the Documents view of ForeFlight Mobile. Select the DOD catalog and scroll to the Supplements section.

More Turbulence Is Better

No, we’re not gluttons for punishment; however, the turbulence Imagery in ForeFlight Mobile has just gotten way better! Forecasts now go out beyond 12 hours to include lead times of 15 and 18 hours. This is a significant improvement to NOAA’s Graphical Turbulence Guidance (GTG-3) product that now includes an analysis and forecast for clear air turbulence as well as turbulence from mountain wave activity with a new forecast updated every hour. Whereas the lowest altitude in the earlier version of GTG originated at 10,000 feet, the new GTG product includes low-level turbulence beginning at 1,000 feet MSL with a vertical resolution of 2,000 feet that extends to FL450. If that isn’t enough, forecasts now have a higher resolution of turbulence intensities that includes the full range of classifications from light to extreme as shown below making the product even more useful to evaluate the risk of dangerous turbulence along your proposed route.

Eddy Dissipation Rate (EDR)

Turbulence intensities now include light (blue to green), moderate (green to orange), severe (orange to red) and extreme (red to dark red).

Eddy Dissipation Rate (EDR)

On the older GTG version, the legacy terminology such as light or moderate turbulence is somewhat arbitrary and based typically on the response of the aircraft to the turbulence, not the atmospheric conditions themselves. Shown in the scale above, Eddy Dissipation Rate, or EDR, is an objective, aircraft-independent, universal measure of turbulence based on the rate at which energy dissipates in the atmosphere. In other words, it is a measure of the turbulent state of the atmosphere. According to turbulence researcher, Dr. Robert Sharman, “When the atmosphere is dissipating energy quickly (i.e the EDR is large), atmospheric turbulence levels are high.” Pilots should be keenly aware that a safe turbulence penetration airspeed varies with the aircraft’s weight which Dr. Sharman quickly points out, “The implication for aircraft bumpiness depends on the size (weight) of the aircraft.”

At the basic level EDR is really an in situ calculation. That is, it is a value determined by an aircraft while in flight. However, it is not directly measured by the aircraft like outside air temperature, for example. Instead it’s determined by using a variety of data from aircraft avionics which means aircraft can (and do) automatically report EDR in flight. Since EDR is an aircraft-independent calculation, a single engine Cessna 152 and a Boeing 747 should determine the same EDR value when flying through the same atmosphere at the same time.

It’s one thing to calculate the EDR in flight, but totally another challenge to provide a forecast for this field. That’s the job of GTG-3. Dr. Sharman points out, “From the forecasting point-of-view we cannot provide a separate forecast for every type of aircraft that is out there.” So depending on the class of aircraft you are flying, there’s a need to evaluate the EDR values properly. Below shows the EDR values that correspond to light-, medium- and heavy-weighted aircraft as they loosely relate to the vertical acceleration/deceleration (turbulence) response in that class of aircraft.

EDR Light

Eddy Dissipation Rate (EDR) scale for light-weight aircraft.

EDR Medium

Eddy Dissipation Rate (EDR) scale for medium-weight aircraft.

EDRHeavy

Eddy Dissipation Rate (EDR) scale for heavy-weight aircraft.

The new version of GTG includes a forecast for clear-air turbulence often referred to as CAT. Even more exciting, turbulence that is a direct result of mountain wave activity, or MTW, is also forecast separately. While these forecasts are not meant to predict turbulence associated with deep, moist convection, they will provide guidance of low-level terrain and thermally-induced turbulence sources.

To that end, in the ForeFlight Imagery view you’ll find three different forecasts that include clear-air turbulence (CAT), mountain wave turbulence (MTW) and one that combines the two (All). Each one of these is organized into low (1,000 ft – 13,000 ft), middle (15,000 ft -FL290) and high (FL310 – FL450) level collections as shown below.

Turbulence Selections

Turbulence forecasts in the ForeFlight Mobile Imagery view are organized by clear air turbulence (CAT), mountain wave turbulence (MTW), and forecasts that combine the two (All). Each type provides low, medium and high altitude collections beginning at 1,000 ft MSL up to and including FL450.

The GTG forecasts have been approved by the FAA for unrestricted use for preflight planning as stated below on the Aviation Weather Center website:

“GTG is generated operationally at NOAA/NCEP which is supported 24 hours a day, 7 days a week. Its use is unrestricted (meteorologists, dispatchers, GA and commercial pilots, ATC, etc).”

Keep in mind that these are automated forecasts and do not have any human input like you might find with AIRMET Tango, SIGMETs for severe or extreme turbulence and Center Weather Advisories (CWAs). When used in combination with these forecaster-generated products and pilot weather reports, GTG will provide you with the ability to minimize your exposure to dangerous turbulence and find the altitude with smoothest ride.