Fooled by the TAF...

[orange]

I booked a plane to fly this morning out of KFRG from 9-11am. No real plan, maybe some touch and gos (just to get some landings in) or a flight to the Hudson. All day yesterday and last night, the TAF was showing 20 kt gusts and light rain and snow for 9am (1300z), and winds increasing to to mid to upper 20's. So I went to sleep and didn't even set my alarm clock for 6:30am. I got up about 8:30, and looked at the METARs and they were showing no rain/sbow and <10 kt winds. All the way up to noon, there was no rain. Then it started raining and lower ceiling.

Lesson learned... don't expect TAF's to be very accurate, it's still only a prediction, an educated guess.

 

[Unit74]

Showed here in Alexandria, VA for a couple hours this AM. Been very windy all day too.....

Can't wait to get outa dis place

 

[Chip Sylverne]

Windy all day? It's been windy all week!

 

[N659HB]

Windy all day? It's been windy all week!

Same here. Hopefully a good flying day tomorrow.

BTW, our TAFs have been depressingly accurate this week.

 

[jordane93]

A day in advanced is still way too early. I don't have my students cancel until an hour prior. Some of my students live a little further away so they'll give me a few hours in advanced.

 

[PaulMKE]

Lately I have been using the model output data (MOS) shown in foreflight in addition to the TAF and discussion to get a clearer idea of what's going on - to triangulate my own idea of what might transpire. Also the NWS is another good data point with the charting tool. Presumably they are all looking at the same data, but sometimes you can divine out the uncertainties.

 

[EdFred]

This is why I only pay attention to pastcasts. Especially in the great Lakes. I've seen every taf in the region and area forecast say OVC040+ and vis 5 or greater, and during that time period ceilings went to under 010 and vis under 3.

I only trust forecasts as far as I can see with my own eyes.

 

[mkosmo]

Lately I have been using the model output data (MOS) shown in foreflight in addition to the TAF and discussion to get a clearer idea of what's going on - to triangulate my own idea of what might transpire. Also the NWS is another good data point with the charting tool. Presumably they are all looking at the same data, but sometimes you can divine out the uncertainties.

The MOS is often no better. I use a number of different models and come to my own conclusions. Having worked for and supported a flight services company (and been the lead on the weather systems) has sure helped, though.

 

[dillardrg]

How far in the future does a forecast have to be to be settled science?

 

[Harold Rutila]

Keep in mind that a TAF is only valid 5SM from the airport. It's a point forecast and one of the most challenging forecasts to make. KFRG doesn't have a TAF. So using the closest TAF isn't always a wise choice. It's also a good idea to read the AFDs which discussed the uncertainty in the forecasts you saw last night.

Exactly. Ironically, the agency heavily emphasizes this to controllers at the academy. I have never had a pilot test question relating to the radius of a TAF, though it is very important.

 

[DavidWhite]

How far in the future does a forecast have to be to be settled science?

1 minute ago

 

[Lowflynjack]

I flew a plane back from Arizona to Texas this weekend. On Saturday, I got stuck in Ozona, TX for five hours! It was overcast at 300'. I watched the TAF change hourly. At first it said it would clear by 10AM, then 11AM, then 1PM, 2PM, and 3PM. It finally got up enough I could safely get out and basically had to fly around a valley where ceilings were low, then I was good. It was a long 5 hours sitting and waiting. Luckily it was a nice terminal with a TV!

 

[danhagan]

I flew a plane back from Arizona to Texas this weekend. On Saturday, I got stuck in Ozona, TX for five hours! It was overcast at 300'. I watched the TAF change hourly. At first it said it would clear by 10AM, then 11AM, then 1PM, 2PM, and 3PM.

I did that in San Antonio 2 years ago. Low overcast (lifting fog) over Stinson and KSAT. Was supposed to be clear by 9am. It was only over the San Antonio area. I finally departed MVFR at 330pm and was in the clear just past the west side of San Antonio. Still need to complete IR ...