Friday, May 1, 2009

Weather...or not?

The forecast for this afternoon at Bridgeport is suggesting gusty moderate winds from the southwest at 2130Z (when I plan to depart) with good visibility in mist and showers. I'm told to expect a 3000 foot broken ceiling, overcast above at 5000 with cumulonimbus clouds. Here's the TAF:

KBDR 011538Z 0116/0212 23010KT 5SM BR OVC006 WS020/24045KT 
     TEMPO 0117/0120 23014G23KT 3SM -RA BR BKN009 OVC020 
     FM012000 24016G22KT 3SM SHRA BR BKN030 OVC050CB 
     FM012300 24012G20KT P6SM SCT030 BKN150 
     FM020100 24009KT 6SM BR SCT012 BKN070 
     FM020400 23008KT 4SM BR BKN012 BKN070 
     FM020900 32006KT 6SM -RA OVC040

The piece of weather that is likely to be over KBDR later is, at this writing, over central Pennsylvania. This is what the State College, PA radar image looks like at 1640Z:

That big yellow blob is headed this way. But there seem to be no lightning strikes associated with it, and the surface conditions are farily mild. As long as it doesn't intensify it will probably be OK to depart once the central part of it has passed...my usual routing will head me to the west over Sparta and out toward Allentown, so I should be going into better conditions.

This all ought to get me into the DC area around 00Z. Here's what the KDCA forecast looks like:

KDCA 011139Z 0112/0212 20012G17KT 6SM BR HZ VCSH OVC013 
     FM011600 21012G17KT 6SM HZ VCSH SCT011 BKN024 OVC035 
     FM011800 21014G23KT 6SM -RA SCT015 BKN040CB 
     FM020000 23008KT 6SM BR FEW020 BKN050 OVC080 
     FM020400 VRB04KT P6SM SCT040 SCT090 
     FM021000 31006KT 5SM -RA BR BKN015 OVC025

OK, that's rain ending about the ETA, going to some mist, few clouds at 2000, good conditions to fly the RNAV 6 approach and may or may not need to circle to land 24.

See you on the other side.


Chip said...

Which weather services do you favor? Are these different than where your Garmin feed comes from?

When you read the KDCA forecast, do you read it as it is displayed on this page, or are you parsing it through a utility. A recent trend in web development is to parse NOAA weather data into human-readable content. This compares to an older method of simply copying an already parsed feed, which doesn't allow for up-to-the-minute data or high level customization.

If you're interested, a sample of such a script can be found here: http://fragmentedzen.com/example/noaa-weather-parser

It's well commented, so you can get a sense of what it spits out.

There are probably a few iPhone apps which do the same.

Frank Van Haste said...

Hi, Chip...

For pre-flight self briefing I use a number of NOAA sites including Forecast Maps from National Centers for Environmental Prediction, and the Model Output Statistics site. Within 24 hours of flight time the Aviation Weather site has all you need.

All the IFR rated pilots I know read the current condition reports (METAR's) and the forecasts (TAF's) in the raw form. It's just a lot more efficient than wading through the verbiage that the natural language parsing engines add. (BTW, I would contend that the raw reports are "human readable" if the human in question is properly trained.)

The Aviation Weather site provides radar graphics created by NWS from the raw return data from NEXRAD and these are useful for flight planning. In the airplane in flight, radar data is displayed on the Garmin 396 as transmitted by XM Satellite Weather. XM gets the images from WxWorx which is a Baron Services company. WxWorx massages the data a little differently than NWS so the colors are a bit different. But red is still bad.

I'll be sure to take a look at the parser you suggest. Thanks.