Flooding Rains In Texas Courtesy Of An MCS

Over the last five or more years a drought of historic proportion has plagued much of Texas. In fact, the National Weather Service reported that 2011 was Texas’ driest year on record. Fast forward to 2015 and that’s hardly been the case over the last few weeks as a good portion of Texas has received more rain in the month of May than they usually receive throughout the entire year. Rainfall totals reported to exceed 20 inches have been pretty common. And to cap it all off, this past Monday a very significant rainfall event occurred throughout central and eastern Texas with more than 10 inches falling in Houston Monday night causing widespread flash flooding in the city. So what caused this extreme rainfall event?

Texas Rainfall

Rainfall totals in May 2015 for the Southern Plains and lower Mississippi Valley. Image courtesy of The Weather Channel.

The phenomenon that was responsible for this deluge of rain on Monday is called a Mesoscale Convective System or MCS. Similar to hurricanes, they are very seasonal. Occurring mostly east of the Continental Divide, they start out in the Southern Plains and Deep South during the month of May. As the jet stream moves north through the summer months of June and July, they tend to occur in the Central Plains, Middle Mississippi Valley as well as the Tennessee and Ohio Valleys. Finally, into July and August, they are seen more in the Northern Plains, Upper Mississippi Valley and Upper Great Lakes regions.

These systems are usually severe and can often produce a few tornadoes, dangerous lightning, large and damaging hail and strong straight-line winds. But perhaps the most devastating feature is the torrential rains that can fall from some of these storms since they are often long-lived weather systems. Nevertheless, these convective systems are absolutely necessary since they provide much of the needed rain for agriculture in the Midwest during the summer months.

MCS on infrared satellite

Many Mesoscale Convective Systems (MCSs) have a signature oval or circular cloud shield as seen on the color-enhanced infrared satellite image. This is the one that provided Houston with over 10 inches of rainfall in just a few hours.

Mesoscale Convective Systems are easy to spot on the color-enhanced infrared satellite found in the ForeFlight Imagery as shown above. When mature, they usually appear as a large circular or oval cloud shield that can cover one or more Midwest states with very cold cloud tops that show up on this image as purple and white. Under this cloud shield is usually a bow-shaped line of strong thunderstorms at the leading edge of the MCS as seen on this NEXRAD mosaic below.

Bow echo associated with the MCS

Often an MCS will have a bow- or crescent-shaped line of echoes which is a good sign of very intense straight-line winds.

You were probably taught that the early morning hours are the best time to fly to avoid thunderstorms. That’s usually sound advice unless you are dealing with an MCS that will often develop and mature in the overnight hours and persist into the next day. So they are often nocturnal beasts that almost seem to create their own environment to feed on.

MCS Pair

The weather system that dumped a copious amount of rainfall on Houston Monday night developed from a pair of thunderstorm complexes in western Texas early that morning. It’s unusual to see a pair of Mesoscale Convective Systems tracking along together.

In fact, the MCS that flooded Houston Monday night was born early that morning in western Texas and began as a pair of MCSs as shown above. Throughout the morning the two systems tracked east and eventually merged (below) into a single complex of storms setting the stage for a very wet evening in Houston.

MCS combined

Just after 12 p.m., the pair of Mesoscale Convective Systems joined up in central Texas to produce one massive convective complex.

This is a very common setting in the Plains where the unique geography of the region favors nocturnal and early morning thunderstorms. During the warm season, this setting promotes a strong flow of low-level moisture northward from the Gulf of Mexico, often referred to by meteorologists as a low-level jet stream. Moisture carried by the low-level jet helps to maintain these systems that often begin during daytime hours on the higher terrain in western Texas and Colorado. Because of the low-level supply of moisture, the MCS can mature and persist well into the nighttime hours.

The Skew-T Log (p) diagram for Houston Monday evening shows the low-level jet as a maximum wind speed at 6,000 feet. This moist, southerly flow keeps the surface dewpoint temperature in the low 70s to offer a good source of moisture for the MCS to ingest.

Skew T Diagram

The Skew-T Log (p) Diagram is an excellent source to visualize the moisture, winds and the instability for a particular location.

Last but not least, the Skew-T diagram shows the atmosphere was very unstable Monday evening with a lifted index of -6, Convective Available Potential Energy (CAPE) approaching 3,000 Joules/kg and a K-Index of 42. A K-Index this high is a good sign of high convective rainfall rates that can produce local flash flooding.

Webinar: Weather Flying and the iPad

Recently ForeFlight’s own Weather Scientist, Scott Dennstaedt, and Sporty’s John Zimmerman hosted a webinar devoted to Weather Flying and the iPad. In this hour long session, learn about the basics of weather, discover how to utilize ForeFlight and the Stratus ADS-B receiver for the most informed and effective weather decision-making, and see ForeFlight and Stratus in action with real-world scenarios. This webinar is geared towards making you a safer, more strategic, and informed pilot in any weather situation.

ForeFlight 7 is Here. Faster Planning, Faster Downloads, and More.

With this release, planning gets even better with a more advanced Procedure Advisor and a dramatically improved navigation database that enables visual preview of SIDs, STARs, approaches, and pattern entries. Downloads are significantly faster and use less disk space. Cabin Altitude Advisor leverages integrated pressure sensors to alert you when things don’t seem quite right. Support for Apple Watch gives you at-a-glance weather, flight instruments, and timers. Our new web-based flight planning system delivers an industry first Web-to-Panel flight planning experience for supported avionics. ForeFlight Mobile version 7.0 is available now on the App Store.

More Efficient Route Planning with Departure, Arrival, and Instrument Procedure Preview 

Our Procedure Advisor tool now allows you to visually preview arrivals, departures, approach procedures, VFR traffic patterns, and Search and Rescue patterns prior to adding them to your route. Procedure preview makes it easy to see how various procedures enter and exit a terminal area.

To use procedure preview, enter a departure and destination in the Route Editor, then tap the Procedure button in the upper right of the Edit view:

Procedure button

A preview window displays the available departures, arrivals, approaches, traffic patterns, and optionally, SAR patterns.

Choose a procedure type to preview.

In this example, tap on ‘Departure (19)’ to view the graphical display of departure procedures out of the Houston area:

Departure procedures out of the Houston area.

The preview begins with a broad overview of the selected airport and geographic guides that outline each direction served by a particular procedure. After selecting an arrival or departure, either in the list on the left or by tapping one on the Map, transitions can be previewed and selected before adding it to the route.

Procedure Advisor also allows you to preview instrument approaches, including a flag on the best wind runway based on the current METAR. Once an approach is selected you can preview different entry points on top of the plate itself. When you are done, simply tap Add to Route.

You can also preview different traffic pattern entries with Traffic Pattern Advisor. The preview flags the best wind runway based on the current METAR and the best side for different VFR pattern entries. Once you have finished adding items to your route, simply tap Close (on the upper right) or tap outside the preview window to hide the Procedure Advisor.

Procedure preview is available on the iPad to Basic and Pro subscribers.

Faster Downloads with Delta Downloads

With ForeFlight 7, we introduce faster and smaller downloads that use less disk space during cycle cross-over time. We call this Delta Downloads and the new system only delivers the ‘what changed’ data each month, resulting in a 70% to 90% reduction in download time without compromising chart quality. Delta Downloads includes terminal procedures, taxi charts, IFR and VFR charts, FAA A/FD, and Canada Flight Supplement data. As Delta Downloads rolls out, you will see the full benefit over the next couple of data cycles. As a customer, there is no action you need to take. Delta Downloads happens automatically for all subscribers.

Stay Safe at High Altitudes with Cabin Altitude Advisor

In the past year, hypoxia and depressurization have claimed pilot lives. We hope Cabin Altitude Advisor helps to prevent future accidents like these. Cabin Altitude Advisor takes advantage of the barometer sensor built-in to iPhone 6, iPhone 6 Plus, and iPad Air 2. The advisor alerts pilots when crossing through 12,000 feet MSL and 25,000 feet MSL. The audio and visual alert triggers once every 30 minutes for each altitude. Pressure Altitude is also available to display in the Instrument panel.

 

A New Look in the Downloads View

In the Downloads view, you will now see VFR charts (TACs and Sectionals) listed by chart name instead of by State.

New look in Downloads view.You can refer to a Chart legend for VFR chart coverage or simply use Pack to ensure that the charts you need for a trip are downloaded to your device.

ForeFlight on Your Wrist with Apple Watch

ForeFlight 7 introduces Apple Watch support, including weather at-a-glance, instruments, and timers.

ForeFlight Lands on Your Desktop

We are excited to announce that ForeFlight flight planning is coming to your web browser. ForeFlight Web Beta enables a full screen desktop experience, automatically syncs to ForeFlight Mobile, and offers seamless Web-to-Panel capabilities via ForeFlight Connect. Our Web-to-Panel concept is a first in flight planning, where web planning activity syncs to your mobile device and loads into the panel of supported avionics like Dynon SkyView.

ForeFlight Web Beta will initially be available to existing ForeFlight customers. We envision this as a very collaborative product development process with our customers. Features will evolve quickly with frequent releases, driven by our vision and by customer feedback. ForeFlight customers who are interested in this Beta program are invited to sign up at www.foreflight.com/web. Invitations to the Beta will be released in phases.

A Layered Approach In ForeFlight

In addition to all of the other great features introduced in ForeFlight Mobile 6.8, we also enhanced the app to allow more layers to be displayed simultaneously on the Map view. Many of these layers are mutually exclusive of one another. That is, when you select a new layer, it will replace the current layer (if any) that was previously selected.  For instance, the app will not allow the Radar and Satellite layer to be displayed at the same time. Therefore, with the Radar layer on, selecting the Satellite layer will deselect and hide Radar layer.

Having this dependency certainly makes sense when selecting between many of the airport-specific layers such as Flight Category, Temperature and Ceiling just to name a few. That dependency hasn’t changed. However, the Pilot Weather Reports (PIREPs) and Lightning layers are not tied to an airport and can now be overlaid individually or together with any of the other Map layers.

Multiple Overlays on Map View

When viewing the Satellite layer, be sure to select Sky Coverage, PIREPs and Lightning for the most complete picture.

This was primarily done to allow users to select the satellite layer while also displaying Sky Coverage along with Lightning as discussed in this earlier blog post. Adding on the PIREPs layer will provide an even greater situational awareness of the weather occurring at any particular location as shown above. If you were to visit the Aviation Weather Center in Kansas City, Missouri, you will notice on the image below that they also make heavy use of overlays.

AWC Overlay Screen

Forecasters often overlay sky coverage and AIRMETs over the visible satellite image.

But if you really want to go crazy, you can select up to seven layers to be displayed at the same time as shown below.  But let’s not go crazy.

Everything Selected

Adding too many layers can render the Map view unreadable.

 

Automated Ceiling Reports

Every day pilots use surface observations to make many routine operational decisions before or during any particular flight. For example, as you approach an airport you have been trained to listen to the ground-to-air radio broadcast to determine the preferred landing runway based on the current wind direction. Or even before you are in radio coverage you may have been following the latest FIS-B METAR broadcast received by your Stratus and displayed in the ForeFlight Mobile app. Many of these observations come from automated systems. So it is critical that pilots at all experience levels understand how these systems collect and process the weather data especially those automated ceiling reports.

Approach-LNS

Listen to the ground-to-air radio broadcast when approaching an airport.

The two primary automated observing systems deployed at many airports throughout the United States includes the Automated Surface Observing System (ASOS) and the Automated Weather Observation System (AWOS). These automated systems like the one shown here consist of a collection of electronic sensors that measure the environment, and then process the data to create an observation once every minute. Even though these automated systems create a completely new observation every minute, they must have adequate sensor samples to develop an accurate observation. In order to provide a representative observation at an airport, the automated hardware must continuously collect the sensor’s real-time data over a period of time. The automated system applies an algorithm to the collected data to extrapolate the weather to cover a wider area.

METAR-ForeFlight

Get the latest observation from ForeFlight Mobile before departing.

This is especially important when considering the observation for sky cover and cloud base height. When approaching an airport, for example, pilots don’t necessarily want to know what’s happening instantly over the sensor since it may not always be representative of the sky condition throughout the airport’s terminal area. Most importantly, it might vary quite a bit between reports.

Automated systems employ an upward-pointing laser beam ceilometer to determine sky cover and cloud height such as the sensor shown here. The cloud height indicator, for instance, transmits a little over 9,000 pulses in 12 seconds, but it’s not these individual samples that are used for the observation. Instead, this data is collected over a period of 30 minutes before a ceiling or sky cover observation is considered acceptable and broadcast to the pilot. So the ceiling report your see on ForeFlight or the one you hear from the ground-to-air radio broadcast is based on a sampling of 30 minutes of data and not the most recent sensor sample taken.

Airports-View-METAR

Automated report in the Airports View in ForeFlight Mobile.

Based on studies, 30 minutes of data provides a fairly reasonable description of sky conditions. This means that the system will detect and process all the clouds (if any) passing over the sensor in the past 30 minutes. To account for the latest sky conditions, the result is biased by counting the last 10 minutes of data twice, a technique referred to as double weighting. Using the last 30 minutes of data in this way will allow the system to determine the height and sky cover included in the surface observation and this becomes a reasonable estimate of the sky conditions that is valid over a three to five statute mile radius around the airport.

Keep in mind that these automated systems have a few important limitations. For instance, automated systems can only report clouds that are below 12,000 feet AGL. This means that an overcast cloud deck at 15,000 feet AGL will be reported as clear. Effectively, a clear sky report from an automated station means the sky is free of clouds below 12,000 feet AGL even though it still may be an overcast day.

Tower-LNS

Towered airport with a trained observer present.

While many high-impact airports throughout the U.S. still rely on a trained weather observer to construct the routine or special observation (SPECI), automated systems supply them with uniform and objective data for the observation. However, automated systems measure only the weather that passes directly through the sensor array so it is not able to report what’s happening outside the airport’s runway complex. Trained weather observers can certainly augment the observation to add these details such as clouds with bases above 12,000 AGL. By the way, the NWS is looking to extend the capabilities of the ceilometer to automatically report clouds above 12,000 feet, but don’t hold your breath; it may take several years before such a solution becomes available.

Customer Notice: Issue with Apple iOS 8.3 and External Bluetooth GPS Receivers

We have learned of an issue with Apple iOS 8.3 that affects some early model Bluetooth GPS accessories, such as the Dual GPS 150 and Bad Elf Pro. When used with iOS 8.3, position information from these accessories may not be delivered to iOS applications, including ForeFlight Mobile.

Stratus and Bad Elf Pro+ devices are not affected. Our friends at Bad Elf have escalated the issue to Apple for resolution.

As a workaround, customers with Wi-Fi + Cellular iPads who have upgraded to iOS 8.3 can disconnect their Bluetooth accessories and rely on the iPad’s internal GPS or Stratus. Customers with Wi-Fi only iPads who have upgraded to iOS 8.3 will need to wait for a resolution, upgrade to a newer GPS accessory, or connect to a Stratus.

We will keep you updated. If you rely on one of these early model Bluetooth GPS accessories, we do not recommend that you upgrade your Apple devices to iOS 8.3.

Fooling Around With Convective Wind Shear

Most pilots equate wind shear to turbulence or convection. Certainly some forms of wind shear are indeed turbulent and convection can also induce dangerous wind shear. If the wind shear occurs close to the surface when the aircraft is landing or departing, it may be in excess of the inertial capabilities of the aircraft making it difficult for the pilot to recover resulting in an accident that is often fatal. But don’t be fooled; some of the most dangerous wind shear situations come out of rather benign-looking convective environments.

Moist low-level outflow from a thunderstorm.

Moist low-level outflow from a thunderstorm.

Perhaps the most dangerous wind shear occurs in a convective downburst where downdrafts in thunderstorms have been estimated to be greater than 100 miles per hour. These high-speed winds strike the surface and spread out creating a gust front that can also be very dangerous especially if it occurs when landing or departing. When that downburst occurs in a very small area spatially (about 2 miles) it is referred to as a microburst similar to the one in this image. Most microbursts are ephemeral lasting no more than five minutes in most cases.

At this point in time, several large turbojet aircraft have succumb to the forces associated with a microburst. The one that is especially memorable is Delta Airlines Flight 191 that encountered a microburst on approach to the Dallas Fort Worth International Airport (KDFW) in 1985. Delta Flight 191 didn’t fly through or under an intense supercell thunderstorm as you might imagine. In fact, a thunderstorm with a cloud base of nearly 10,000 feet was the culprit. High-base convection with a heavy rain signature should be of particular concern to pilots since they signal a deep mixed layer with a high lapse rate and plenty of precipitation to fuel a strong downdraft. Pilots can be fooled because high-based convection does not seem particularly threatening (especially to pilots flying large turbojet aircraft) which makes them even more likely to stumble into the path of a downburst or microburst.

Here’s a quote from a paper written by Captain William W. Melvin entitled Wind Shear Revisited, Air Line Pilot Magazine, Nov 1994.

Many pilots have been trained to avoid large supercell-type thunderstorms in the belief that this will prevent encounters with microbursts. Yet no evidence exists that any of the known microburst encounters have occurred in supercell storms. Dr. Ted Fujita and Dr. Fernando Caracena recognized authorities in this field have repeatedly emphasized that microbursts are frequently generated from benign-appearing cells. Many “experts” who disagree with Drs. Fujita and Caracena have emphasized the supercell storms with warnings of dangers of gust fronts. These so-called experts are leading pilots down the primrose path for microburst encounters.

In a high-based thunderstorm there’s typically an extremely dry environment between the cloud base and the surface. Initially, little or no rain may reach the surface. As the rain falls out of the cloud into this very dry atmosphere it evaporates quickly which causes a cooling effect relative to the air around the precipitation. Such cooling makes the air much denser, and therefore negatively buoyant, effectively creating a very intense downburst with winds that may exceed hurricane force, even approaching the speeds found in a weak to moderate tornado.

The next time you see what appears to be a very inviting situation in and around active convection, think twice about departing or making that approach to land. Microbursts can happen quickly before any visual cue may exist. Especially avoid areas where you see a circular ring of dust at the surface that may be curled around the edges or any kind of bulge (piling up) of precipitation at the bottom of an evolving rain shaft. These are all characteristics of a intense downdraft, microburst or gust front.

Expanded Taxi Chart Coverage, Taxi Chart Improvements Land in ForeFlight Mobile 6.8

We are pleased to announce that ForeFlight Mobile version 6.8 is now available for download on the App Store! This update focuses on improving airport surface operations with more taxi chart coverage and more information on taxi charts for improved guidance. A new ownship setting makes compliance easy for customers operating under the guidance of FAA AC 120-76C. Version 6.8 also moves the app to a new minimum level of iOS support, paving the way to better product efficiency and more feature capability in the future.

FBOs on Taxi Charts

Taxiing to the FBO just got easier—over 2700 FBO locations are now mapped on both FAA and ForeFlight Airport Diagrams for better ground-based taxi guidance. When coupled with ownship display capability in ForeFlight Mobile Pro, you can easily see where your aircraft is in relation to the FBO. We continue to add more FBO markers with each Business Directory update.

(Edited 4/13/15: ForeFlight Mobile version 6.8.1 is now available on the App Store and resolves the issue where FBO markers were not displaying on ForeFlight Mobile Basic accounts.)

FBOs on Airport Diagram

FBO markers shown on the airport diagram for Houston’s Hobby Airport.

While viewing a taxi chart, tap on any FBO marker to see detailed information, including photos, fuel prices, contact information, and more. FBO markers will appear on taxi charts within the Plates view and also when displaying a taxi chart on top of the moving map.

FBOs on Airport Diagrams detail view.

Tap on the FBO marker to reveal detailed location information.

You can choose to show or hide the FBO markers using the FBO button on the Plates view:

Turn FBO overlay on or off in the Plates view.

Turn FBO overlay on or off in the Plates view.

Or on the Maps view, tap anywhere on the taxi chart to open the pop-over menu and toggle the Show FBOs button ON or OFF:

Turn FBO overlay on or off in the Maps view.

Turn FBO overlay on or off in the Maps view.

If you are an FBO and would like to place your marker, login to your ForeFlight Manage account or contact directory@foreflight.com to set up an account.

FBOs on Airport Diagrams is available to Basic and Pro subscribers; ownship position on geo-referenced airport diagrams is a Pro feature.

Expanded Taxi Chart Coverage

We continue to invest in expanding our taxi chart coverage, providing taxi charts for airports not mapped by the FAA. As of this release, we have added more than 1,700 ForeFlight taxi charts—more than tripling the coverage provided by the FAA alone! Our airport mapping team continues to expand ForeFlight’s library, giving you more coverage at more airports. Combined with the new FBO display on taxi charts, finding FBOs at airports is easier than ever.

Easy Ownship Compliance Support for Operations Under FAA AC 120-76C Guidance

Ownship depiction with runway proximity advisor.

Approval for ownship display on airport diagrams is a huge safety enhancement for Part 135 and 121 operators.

ForeFlight now makes it easier for our certificated FAA Part 91F, 91K, 121, 125 and 135 customers to comply with ownship display limitations as defined in FAA AC 120-76C operational guidance for use of electronic flight bags.

These operators are limited to using ownship depiction during airport surface operations and at less than 80 knots ground speed.

To access the setting, navigate to the More > Settings view, then scroll down to Preferences and tap on Enable Ownship. The ownship setting options include: Always, Never, and Limited. Limited mode automatically applies the speed-restricted display function as described in the Advisory Circular. Once airborne, the ownship display icon is automatically removed from view. 

New ownship setting for easy compliance.

New ‘Limited’ ownship setting makes it easy to comply with FAA AC-120-76C guidance.

If your flight operation is not taking advantage of ownship display on taxi diagrams, we have the tools and resources to help you get going. Email sales@foreflight.com for more information.

ForeFlight 6.8 requires iOS 8 or higher

Please note that ForeFlight Mobile 6.8 requires iOS 8 or higher. By moving to iOS 8 as the minimum supported iOS version, we can deliver new features enabled by the Apple update, deliver smaller application downloads, improve energy efficiency, improve support for devices like the iPhone 6 Plus, and deliver faster application performance. 

If you would like to take advantage of the new features in ForeFlight Mobile 6.8 or later, you will first need to update your device to the current iOS 8.x version. Apple posted this helpful article with instructions on how to update your iOS device to iOS 8.

For those of you running Apple iOS 7.x or earlier versions, you will still be able to use your current version of ForeFlight Mobile. After ForeFlight Mobile 6.8 is released, if you need to reinstall ForeFlight on an existing device you can download the last compatible version of ForeFlight Mobile from the App Store. If you have any questions, please contact us at team@foreflight.com.

The only device that is not capable of upgrading to iOS 8 that is currently also supported by iOS 7 (the current minimum iOS requirement for ForeFlight Mobile) is iPhone 4.

Blue skies!

Density Altitude: The Secret Killer

Now that the warm season is approaching, pilots need to start planning for the secret killer, namely, density altitude. In fact, density altitude (DA) is perhaps just as hazardous as airframe icing. In an NTSB study, density altitude contributed to just as many accidents as icing shown in the pie chart below. To be fair, some of the accidents in the NTSB study that were attributed to density altitude were caused by pilots departing in an over-gross weight aircraft or using improper procedures (e.g., improper flap usage). However, every pilot needs to be aware that gross mistakes such as this are not forgiving when the density altitude is high.

NTSB-Wx-Accident-Study

What is Density Altitude?

In simple terms, density altitude is pressure altitude corrected for non-standard temperature. Therefore, if the pressure and temperature throughout the atmosphere matches the standard, then pressure altitude and density altitude are equal. Of course, during the warm season, the temperature is generally above standard in most locations throughout the U.S. creating an invisible hazard if ignored.

If you’ve ever flown out of a high-elevation airport such as Santa Fe, New Mexico (6,348 feet MSL), you have experienced the effect of density altitude. At these airports, the performance of the aircraft decreases. For fixed-wing aircraft you will experience a longer takeoff distance, longer landing rollout and reduced rate of climb. The higher you are above sea level, the lower the pressure and that means the air is less dense. This reduction in air density reduces the wing’s lift and also lowers the efficiency of the propellor or rotor.

What About Temperature?

The temperature of the air can have the same effect even at sea-level airports. As daytime temperatures begin to creep up into the upper 80s and 90s, the air becomes much less dense similar to being at that high-elevation airport. That means there are fewer air molecules in a given volume of airspace. Less air, means poor aircraft performance similar to what was described above. And of course, the combination of high temperatures at high-elevation airports can make for a serious hazard waiting to happen if unchecked.

While a pilot can determine pressure altitude in the cockpit by setting the altimeter to 29.92″, there’s no handy-dandy instrument that you can use to directly measure the density altitude. It must be calculated based on the station’s pressure (not the altimeter setting), temperature and dewpoint temperature. Not to worry, the ForeFlight Mobile app does all of the work for you.

Finding Density Altitude in ForeFlight

To find the density altitude simply select an airport from the Maps view. In the pop-over window, tap the METAR tab at the bottom and scroll down a bit to see the current density altitude for the chosen airport.

Density-AltitudeJust like any other aspect of weather, pilots need to prepare in advance. Before you close the door to the cockpit, double-check the density altitude in ForeFlight to be sure it won’t adversely affect your flight. To learn more about density altitude, please refer to this FAA safety publication.