Historical Winds and Longer Range Forecast Winds Now in ForeFlight

ForeFlight customers now have access to more winds aloft data for more accurate long term flight planning.

Seven Day Winds Forecast
The winds aloft forecast data in ForeFlight now extends up to seven days in the future (previously 30 hours), giving you more accurate route performance calculations for flight plans within that timeframe, anywhere in the world. The additional high-resolution Global Forecast System (GFS) data is available now for all ForeFlight customers and is automatically incorporated into route performance calculations.

Historical Winds
When your flight is more than seven days away, ForeFlight now gives you the advantage of historical winds aloft data. Historical winds are derived from monthly average winds over the past 40 years. This means that when you plan a flight that uses historical winds, ForeFlight assumes the same wind speed, direction, and temperature for every day and time within a given month; move the departure time to a different month and ForeFlight automatically adjusts the value based on the average for that month. You’ll know when ForeFlight is using historical winds by the yellow banner across the top of the Flights view.

ForeFlight historical winds alert

It is worth noting here that, unlike the seven day wind forecast, currently only the Flights view uses historical winds. When planning in the Maps view, ForeFlight will assume zero winds if you’re planning a flight more than seven days in advance. However, you can easily send your route plan from the Flight Plan Editor in the Maps view to the Flights view and ForeFlight will automatically re-calculate route performance using historical winds. In addition, ForeFlight on the web uses historical winds for flight planning beyond seven days in the future.

ForeFlight use the Send To feature

Use the Send To button to move your route plan from Maps to Flights.

Seamlessly integrating the GFS seven day wind forecast and monthly historical winds provides ForeFlight customers with more accurate data for planning a flight, whether it’s next week, next month, or next year.

The Changing Of The Progs

As mentioned in the ForeFlight blog back in June, the familiar prog charts pilots use every day will be changing. Hopefully you’ve had a chance to test drive these new NDFD prog charts that were introduced in ForeFlight Mobile 7.1. Beginning this morning (September 1, 2015) the precipitation forecast on these charts will now originate from meteorologists at the local NWS forecast offices and not from meteorologists at the Weather Prediction Center (WPC). For more information, you can read the official NWS notification.

Still a forecast for precipitation coverage

The precipitation shown on the new chart represents an instantaneous precipitation forecast. That is, it shows expected likelihood and coverage of precipitation (including type) at the valid time on the chart.  Essentially the light shaded areas define at least a 15% chance and dark shaded areas define a 55% or greater chance of precipitation reaching the surface in that period. A legend in the lower-left corner designates the likelihood of precipitation (chance versus likely) as well as the precipitation type (snow, rain, mix, thunder, etc.). Nevertheless, the isobaric forecast along with high and low pressure centers and a forecast for the position of surface fronts will continue to be issued by the same meteorologists at the WPC.

Prog Chart Change

Legacy prog charts (left) are being replaced with the new NDFD Progs (right).

For better or for worse?

It goes without saying that not every change is necessarily an improvement. It’s not that the other precipitation forecasts were bad; however, given that the precipitation forecast on this new chart is generated by meteorologists at the local forecast offices, it will be more consistent with the terminal forecasts (TAFs) and the local weather forecasts from weather.gov since the TAFs and local weather forecasts are issued by those same local meteorologists. Perhaps the biggest drawback of the new imagery is that the precipitation forecast now ends at the U.S. border although the isobaric forecast and forecast for surface fronts will still cross over into Canada, Mexico and coastal waters.

Here’s what we did in ForeFlight

Given that the legacy prog charts are no longer issued, we’ve moved the new prog charts from their initial home under the NDFD Progs collection to the Prog Charts collection where they will replace their legacy counterparts. Note that the extended forecast progs (Day 3 through Day 7) located in the Prog Charts collection will not be affected.

Prog Layout In ForeFlight

The result in ForeFlight is a single prog chart collection consisting of the latest surface analysis, new NDFD progs (6 to 60 hours) and the extended progs (Day 3 through Day 7).

GFS MOS Forecast Update

In this recent blog we presented a round-robin VFR flight from Oshkosh to International Falls. The concern was not the initial leg, but the return flight three days later. Would ceilings permit a VFR flight from International Falls back to Oshkosh on Saturday? The 75-hour GFS MOS forecast below provided clear guidance that a morning return would not be very likely given the IFR ceilings forecast along this route. But what really happened?

Ceiling forecast

Original 75-hour GFS MOS forecast valid at 1500 UTC for the return flight Saturday. This clearly shows that a VFR flight from International Falls to Oshkosh will not be possible in the morning.

Turns out the GFS MOS was spot on with the ceiling forecast as shown below on ForeFlight Mobile. While low IFR conditions were much more widespread than forecast, much of the region forecast to be in the marginal VFR flight category or lower were indeed at or below marginal VFR.

Actual Ceilings at 15Z

Actual ceilings at 1500 UTC as shown on ForeFlight.

How about later in the afternoon? The 81-hour GFS MOS forecast below valid at 2100 UTC suggested the low IFR ceilings would give way to VFR ceilings making a VFR flight possible later in the afternoon.

Afternoon CIGs

Original 81-hour GFS MOS forecast valid at 2100 UTC for the return flight Saturday. This guidance shows that ceilings were expected to improve later in the afternoon.

By 2100 UTC as shown below in ForeFlight, ceilings began to lift and mix out throughout the early afternoon giving rise to VFR conditions along a good portion of the proposed route of flight. However, there were some marginal VFR conditions still remaining in the vicinity of International Falls and Oshkosh with a few stations reporting ceilings slightly below 2,000 feet. It took a couple more hours before the entire route was truly VFR. Still, that’s not a bad forecast for 3 days out with an error of just a few hours.

Actual-CIGs-Afternoon

The ceilings in the vicinity of the departure and destination airports remained slightly below VFR at 2100 UTC, but most of the route cleared as expected.

While the GFS MOS guidance won’t provide this kind of clarity every single time, it does a surprisingly good job most of the time. Give it a go on your next round-robin flight.