PoP Goes The Forecast

When we make a decision to depart on any round-robin flight, it’s not unusual to also factor in the expected weather on the return trip. If the return leg doesn’t look very good, what’s the sense in making a flight that may put us in a compromising position later on. But if that flight is three or more days in the future, how do you know that it’ll be safe to fly back home? That’s a difficult question to answer because at three days and beyond there really isn’t any aviation-specific weather guidance that can tell you about adverse weather elements such as low ceilings and/or low visibility, airframe icing and turbulence. That certainly leaves pilots to fend for themselves.

If you want to stack the deck in your favor and choose the best time to minimize your exposure to adverse weather you should focus in on areas of precipitation. Of course, not all precipitation events are considered hazardous, but many are, especially when flying VFR. That’s because adverse weather elements such as IFR conditions, icing, turbulence and thunderstorms tend to occur in and around areas of precipitation. So it’s a good bet that if you find yourself faced with precipitation forecast along your proposed route, you will likely encounter some form of challenging weather, even if your planned flight is several days from now.

So that’s why in ForeFlight Mobile 7.1 we introduced the 12 hour Probability of Precipitation forecast like the one shown below. It’s known as the PoP forecast and you’ll find it in the USA CONUS Imagery view under 12 HR PoP.

Probability of Precipitation forecast

This is the 12 hour Probability of Precipitation (PoP) forecast. You can find this on ForeFlight under the Imagery view in the 12 HR PoP collection.

This forecast is issued by meteorologists at the Weather Prediction Center (WPC) in College Park, Maryland. It’s the same group of forecasters that issue the familiar prog charts pilots have used for many years. It’s designed to show the forecaster’s confidence of where precipitation will likely reach the surface within a 12 hour forecast period. The higher the numbers shown on the forecast, the higher the chances (probability) precipitation will occur in that period.

It’s important to understand the date-time stamp on the forecast. Many precipitation forecasts are valid over a period of time. In this case, the period is 12 hours. The valid time in the lower left of the chart is the ending time of the 12 hour period. In this case the forecast is valid from 12Z on June 1st through 00Z on June 2nd. This basically covers the daytime hours on June 1st.

While the short-range surface prog charts generally cover the weather features and precipitation expected over the next two days, the 12 hour PoP forecast describes the medium- to long-range forecast. It starts with Day 3 (the day after tomorrow) and runs through Day 7 with 12 hour forecasts ending at 00Z (daytime) and 12 hour forecasts ending at 12Z (nighttime).

Let’s say you were planning a flight from Chicago to Atlanta during the day on June 1. Using the 12 hour PoP forecast above, there’s a good chance you’ll face challenging weather along that route. On the other hand, if you were flying from Chicago to Oklahoma City, the likelihood of any significant adverse weather is minimal.

That’s not to say that most of the significant weather may end up occurring during the late afternoon on that flight to Atlanta. So a morning flight may still be possible. But this forecast doesn’t provide that level of temporal resolution. Moreover, even though the flight to Oklahoma City looks promising, you could still face IFR conditions, icing (during the cold season), strong winds or the potential for turbulence. So you can’t become complacent.

Day 3 Prog Chart

Use the Day 3 Prog chart along with the 12 hour PoP.

In that light it’s useful to also look at the Day 3 prog chart shown above (Day 3 through Day 7 progs are now located in the Prog Charts collection). Forecasters don’t show areas of instantaneous precipitation on the Day 3 through Day 7 progs, but what you do notice is that most of the precipitation shown on the 12 hour PoP forecast is along and ahead of the stationary front that extends from the Eastern Shore of Maryland southwest to Houston, Texas. Therefore, much of this precipitation is associated with a large scale synoptic feature which means plenty of dynamic forcing and likely the reason the probabilities are so high.

Also notice that behind the front the precipitation chances decrease and become nearly zero through Illinois and Missouri. This is courtesy of a rather large area of high pressure seen on the Day 3 prog with an inverted ridge spilling down from Ontario, Canada into central Texas. Such a ridge promotes subsidence or sinking air. Air that is sinking tends to inhibit the formation of clouds and tends to keep the air stable. While you can’t rule out early morning radiation fog or some moderate thermal turbulence in the afternoon, the chances of any significant turbulence aloft is minimal under a ridge. Lastly, the pressure gradient (distance between isobars) is fairly large implying a low risk of strong and gusty winds.

Pilots have never really been all that skilled using long-range forecasts. That’s understandable since a pilot’s primary training mainly focused on making a go or stay decision moments before departure. Very little time is spent on how to analyze the weather more than 24 hours in advance. But these long-range forecasts can provide some valuable planning information especially if your timing is flexible. Or if it’s not flexible, a bad decision now might tempt you to fly when the weather is hazardous later on for your return trip. Here at ForeFlight we hope that the 12 hour PoP forecast will provide the guidance you need for that long-range flight planning.

Bulletin: June 5 Data Updates

An updated Ontario Taxi Diagram and A/FD download is available for the April 30, 2015 – June 28, 2015 period. This update adds two CFS entries for offline use: CYQK and CYVZ. We have also updated the Pilot’s Guide to ForeFlight Mobile in the Documents Catalog.

All customers who have these selected will be prompted to download them inside of ForeFlight Mobile.

New Pilot Scores Sporty’s Sweepstakes Plane with ForeFlight Purchase

Sporty's Michael Wolf congratulating sweepstakes winner Rick Okikawa.

Last month we participated in Sporty’s Annual Fly-In and enjoyed free food, fellowship, flying—and a special surprise. Always a highlight of the event is the announcement of the airplane sweepstakes winner. Sporty’s customers are automatically entered into the sweepstakes each time they make a purchase. This year that winner was Rick Okikawa from Sacramento, California. Rick’s winning purchase was a ForeFlight subscription bought on a whim when he ran into his flight instructor one day.

I had the opportunity to chat with Rick about his big win and what his plans are for his new plane:

“I was struggling looking at TFRs and my instructor happened to pass by and asked if he could help. He immediately saw what I was trying to do and said, ‘Wait, you don’t have ForeFlight? Let me show you what you can do’,” explained Rick. “He proceeded to pull out his iPad and started showing me everything from TFRs to airport details in the Directory. I immediately purchased an iPad and called up Sporty’s the same day to order ForeFlight.”

Rick considers himself new to flying, having started part-time about three years ago flying with the Cal-Aggie Flying Farmers out of the University of California Davis. In July of 2014 he sealed the deal, completing his flight training and becoming a licensed pilot.

“I’ve always had the interest and always wanted to fly. You can always make excuses—not enough time, not enough money. Things just fell into place for me; I had the time, I had the money, I didn’t have any more excuses to not fly.”

When I asked him about the winning phone call he received from Sporty’s, he said he thought it was a scam at first. And who could blame him? It’s not every day you get a call from someone trying to give you a new airplane!

What does Rick have planned for his new ride? “Currently my favorite places to fly are along the coast: Mendocino, Little Rivers, Monterrey, and flying the bay tour. I am looking forward to having the freedom to just get out and go when I want and not have to plan ahead to reserve a plane. I’d like to do some cross-country flying, and would even like to start training for mountain flying so I can take a trip to Lake Tahoe through the mountains.”

We thank Sporty’s for another unforgettable fly-in; we had a great time and it’s an event we’re sure Rick won’t forget either. Congratulations, Rick—wishing you blue skies in the new RV-12!

Our Weather Imagery Has Blossomed

Browse the Imagery view in ForeFlight Mobile and you will notice big changes have taken place! In addition to some basic spring cleaning, we nearly doubled the number of collections in the USA Ensembles.

What are all these new charts?

Like anything else that’s new, it’ll take some time for you to fully benefit from all of the imagery we’ve added to the ForeFlight Mobile app. We understand that some of these new charts may be unfamiliar to many customers. Therefore, in the weeks and months to come you can expect to see us offer more insight on how to effectively use this guidance in your day-to-day preflight planning regiment. So stay tuned to Twitter, Facebook, and the ForeFlight blog for more details.

12-hour Probability of Precipitation

Shown here is one of the new forecasts included in the USA imagery ensembles called the 12 HR Probability of Precipitation or 12 HR PoP for short.

What’s with the order of the collections?

Previously in ForeFlight Mobile, the USA collections were roughly ordered alphabetically with Alaska being first and Winds Aloft positioned last. With such a large number of new collections, we want to do a little better than to simply alphabetize the weather guidance. While there is no perfect way to order these collections to meet every pilot’s needs, we implemented an order that we think you will find useful. Here’s what we were thinking…

Picture a preflight weather briefing as a funnel with large-scale features at the top of the funnel and route-specific details at the bottom.  At the top of the funnel you start out with the synoptic overview (big picture) such as the location and movement of high and low pressure systems, fronts and associated areas of precipitation and clouds. The timing of your proposed round-robin flight is often critical, so we’ve placed outlooks and long-range forecasts near the top as well to help you decide which day may provide the best opportunity to minimize your exposure to adverse weather. As you work your way to the bottom of the funnel, this will include finer route-specific details such as en route advisories to include G-AIRMETs and SIGMETs, icing, turbulence, regional satellite, ground-based radar and last, but not least, pilot weather reports.

What happened to my favorite and recent images?

We made an honest attempt to preserve all of your favorite and recent images with this update. A careful mapping was done to point to the right image even for those that were moved from one collection to another. There were also a dozen or so images that existed in more than one collection; so we removed those duplicates. If your favorite image was the one we removed, it was mapped to the other location. Nevertheless, there may be a few images that were deleted and a few favorites or recents that were not preserved. If you are having trouble finding one of those images, please e-mail us at team@foreflight.com and we are happy to track those down.

Speaking of recents and favorites, there is now a recents button for imagery on the iPad version of the app as shown below. Now you can view and swipe through all of your favorites and recents on your iPad or iPhone. These settings sync across your mobile devices. As always, don’t forget to check out the Pilot’s Guide to ForeFlight Mobile to learn more about the new imagery.

 

 

Double the Weather Imagery, FreeFlight ADS-B Connectivity, More Flexible Download Manager in ForeFlight Mobile 7.1

ForeFlight Mobile version 7.1 equips you with more weather briefing and analysis tools in the Imagery view to make better go/no-go decisions, delivers subscription-free weather and ADS-B traffic via FreeFlight Systems’ certified RANGR-series ADS-B products, and gives you more options to manage chart downloads.

Enhanced Weather Image Library

We are a company of pilots and so we understand that weather is a top priority when it comes to flight planning and decision-making. Having our own in-house Weather Scientist (Scott Dennstaedt) allows us to focus on advancing the capabilities of the preflight weather briefing tools within the ForeFlight platform. Scott and the development team have been busy thoughtfully organizing ForeFlight Mobile’s Imagery and nearly doubled the number of collections in the library. Eight new weather image sets are available and include forecasts for ceiling and visibility, convection, and precipitation. Additionally, products like icing, turbulence, and AIRMETs are enhanced with greater resolution of altitude and/or time.

This article from Scott provides an introduction to the new weather imagery collections.

Over the next few weeks we will provide more guidance and insight on how to effectively use these weather products in your day-to-day preflight planning regiment. So stay tuned to Twitter, Facebook, your email inbox, or right here on the ForeFlight blog for more details. The Pilot’s Guide to ForeFlight Mobile is also a great resource to learn more about the new weather imagery collections.

Recents button in Imagery viewWe have also added a Recents button to Imagery view on the iPad version of the app. Now you can view and swipe through all of your favorites and recents on your iPad or iPhone. For those of you that move between devices while planning, these settings sync so that you can easily pick up on your iPad where you leave off on your iPhone (or vice versa).

The new forecast weather products are available to all subscribers.

Need a refresher on those weather chart symbols? Grab the current Aviation Weather Services Advisory Circular from the Documents catalog:

Aviation Weather Services

Refresh your weather symbology knowledge with the Aviation Weather Advisory Circular in ForeFlight Documents.

Test Drive the New Prog Charts

New Prog Charts

Test drive the new NDFD Progs.

The Prognostic Charts that pilots have known and used for years are undergoing a facelift this Fall. As part of the Imagery enhancements, we are including these new charts giving you a chance to become familiar with them before they are officially released by the National Weather Service. Read this article from Scott where he walks through the new features of this helpful weather prediction chart.

FreeFlight RANGR-series ADS-B Solutions Deliver Weather and Traffic to ForeFlight Mobile

Our ForeFlight Connect program now includes FreeFlight Systems’ RANGR-series of certified ADS-B products. The FreeFlight Wi-Fi connectivity solution enables you to affordably equip your aircraft well in advance of the FAA’s 2020 mandate and immediately realize the benefits of inflight subscription-free FIS-B weather and TIS-B traffic on your iPad or iPhone. The RANGR GPS receiver also provides position source and data for the ForeFlight Mobile moving map view and instrument panel. ForeFlight Mobile is compatible with any certified FreeFlight Systems product that has the capability to receive data. This includes the FDL-978-RX, FDL-978-XVR, and FDL-978-XVR systems.

Delta Downloads and Download Manager Enhancements

We have received lots of positive feedback on Delta Downloads and the 70%-plus increase in download speed that the system delivers. With 7.1, Delta Downloads is activated on all customer accounts. In addition, the Delta Downloads infrastructure enables some helpful changes to the way US VFR charts and IFR Enroute charts can be managed in the Downloads view.

New Downloads grouping by State.

IFR High and Low Enroutes and US VFR charts are grouped by State or Province.

We have made it easier to manage these charts both as individual downloads or grouped by State or Province. Tap the rotating caret to reveal individual charts in a State or Province group.

New section header showing Packed data.

New section header showing Packed data.

A new heading—“Packed and Unselected Regions”—contains charts you have Packed, as well as those you regions you may have de-selected. The re-organization makes it easier to see charts you may want to delete or unpack.

Apple iOS 8.4 Expected To Resolve GPS Accessory Compatibility Issue

As noted in a previous blog post and via a customer notice email, iOS 8.3 introduced an incompatibility with previous generation GPS accessories like the DUAL XGPS 150 and some Bad Elf devices. The issue was escalated to Apple by ForeFlight and Bad Elf and, based on PIREPs we have received, is expected to be resolved in the forthcoming iOS 8.4 update. This issue has frustrated many pilots who own Wi-Fi only iPads or GPS accessories, and we are glad relief is on the way.

Related Articles

Our Weather Imagery Has Blossomed

Prog Charts Are Changing

Prog Charts Are Changing

The Prog Charts that pilots have been using for the last decade or two (pictured below) will be undergoing a facelift sometime in September 2015.

Old-Progs

So at ForeFlight we’re giving you the opportunity to test drive the new charts before they become operational and are officially released by the National Weather Service (NWS). We’ve added these forecasts to our USA Ensemble Imagery and you can find them under the NDFD Progs collection as shown below.

NDFD-Progs

So What’s Changing?

The current Prog Charts are issued by highly experienced meteorologists at the Weather Prediction Center (WPC) in College Park, Maryland; that won’t change. The new implementation will still use the fronts and sea level pressure (SLP) forecast issued by those same meteorologists at the WPC, however, the precipitation forecast represented by those pale green lines is being replaced. The new instantaneous precipitation forecast is now being extracted from the National Digital Forecast Database (NDFD). Instead of the green contours, you’ll see the new precipitation forecast as shaded and outlined regions like the ones shown below.

New Prog chart

Example of the new NDFD Progs.

The new NDFD Prog Charts contain a mosaic of digital precipitation forecasts issued from all of the local NWS weather forecast offices (WFOs) throughout the United States working in collaboration with the National Center for Environmental Prediction (NCEP) and WPC. The forecasts depicted combine the familiar WPC forecasts of fronts, isobars and high and low pressure centers with the NDFD depiction of expected weather type and likelihood.

The precipitation presented on the new NDFD Progs is forecast coverage just like its legacy counterpart. So it is valid at the time posted on the chart and not over a period of time. Using a color-coding, the legend in the lower left corner of the image describes the precipitation type or weather expected (rain, snow, mixed, ice and thunderstorm) as well as the likelihood (chance versus likely) that the precipitation will occur.

Precipitation type legend

Definitions for the various weather types depicted on the NDFD Progs.

We know that it’ll take some time to become completely comfortable with the new forecast depiction of precipitation, but give them a try now so you’ll be way ahead of other pilots come September.

Update: iOS 8.4 Expected To Resolve GPS Accessory Compatibility Issue

UpdateAs part of the June 2015 WWDC, Apple announced that iOS 8.4 arrives on June 30. This version includes a fix to the Apple Bluetooth GPS bug.

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As noted in previous blog post and via a customer notice email, iOS 8.3 introduced an incompatibility with previous generation GPS accessories like the DUAL XGPS 150 and some Bad Elf devices. The issue was escalated to Apple by ForeFlight and Bad Elf and expected to be resolved in the forthcoming iOS 8.4 update, based on PIREPs we have received. This issue has frustrated many pilots who own Wi-Fi only iPads or GPS accessories, and we are glad relief is on the way.

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.

Bulletin: May 28 Data Updates

Data updates are now available to download for the May 28, 2015 – June 25, 2015 period:

  • Airport and Navigation Database
  • Documents, including the AOPA Fly-In Frederick NOTAM
  • ForeFlight Airport Diagrams
  • VFR Charts and Terminal Area Charts
  • World Area Charts
  • Taxi Diagrams
  • Terminal Procedures
  • Airport/Facility Diagrams
  • Documents

Data updates are also available for our Military Flight Bag customers:

  • Global airport, navigation, and airway coverage from the Digital Aeronautical Flight Information File
  • Georeferenced worldwide D-FLIP Terminal Procedures
  • Georeferenced worldwide D-FLIP Airport Diagrams
  • EEA High Enroutes, Area Charts
  • ENAME High and Low Enroutes, Area Charts
  • Airfield Qualification Program (AQP) diagrams
  • Airfield Suitability and Restrictions Report (Giant Report)
  • Airport/Facility Directory

All customers will be prompted to download these updates inside of ForeFlight Mobile.