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Would You Go? Ceilings Are 2000' With 4SM Visibility And Light Snow

Making go/no-go decisions isn't always easy. With winter weather approaching, take a look at this scenario, make your decision, and tell us what you'd do at the bottom of the article...

Swayne Martin

The Flight Scenario

You're an instrument rated private pilot, but not instrument current, and you need to fly your Cessna Skyhawk from Eau Claire, Wisconsin (KEAU) to Hutchinson, Minnesota (KHCD) for a friend's wedding reception. You have an important speech to make, and you can't miss the event. The plane is in perfect condition and IFR certified, but is not equipped for flight into known icing conditions.

When you wake up, you notice there's a band of light snow moving through the area which you didn't anticipate the night before. The weather is reporting Marginal VFR at the destination with VFR conditions along the whole route.

Some airports to the north and south are reporting IFR conditions due to light snow and poor visibility.

If you don't fly, you won't have enough time to drive to the reception in time. You've flown over the Minneapolis area before, but have never been into Hutchinson, MN. There's no terrain along the route, and the reported ceilings are VFR along the entire route. The band of snow is moving slowly east through the area, and there's no hope of "waiting it out" for a few hours.

ForeFlight

Red dots indicate IFR conditions, blue dots indicate MVFR conditions, and green dots indicate VFR conditions.

Upon reaching Hutchinson, diverting north isn't an option, due to IFR conditions and an AIRMET ZULU for icing conditions. Diverting south towards Mankato isn't a realistic option either due to the same circumstances. If you can't land in Hutchinson, you'll either need to turn around towards Minneapolis or continue to the West of the snow bands.

Here's the current weather along the route:

  • KEAU METAR (Departure): 101956Z 00000KT 10SM OVC110 M07/M13 A3027 RMK AO2 SLP268 T10671128
  • KMSP ATIS (Enroute Mid-Point): 101953Z 17010KT 10SM OVC060 M06/M13 A3024 RMK AO2 SLP 257 T10611128
  • KHCD METAR (Destination): 101955Z AUTO 12012KT 4SM OVC020 -SN M07/M11 A3020 T10731110
  • KGYL METAR (13 miles southeast of destination and reporting VFR): 101955Z AUTO 12009KT 6SM OVC040 6SM -SN M07/M11 A2020 T10721110
ForeFlight

Your Legal Requirements

VFR cloud and visibility requirements are determined by time of day, altitude, and airspace. Your route will be flown during the middle of the day. Depending on how high you want to fly, you'll either be flying in Class G or Class E airspace for the majority of the flight. You'll also likely fly through Minneapolis' Class B Airspace. These are your daytime VFR weather minimums:

  • Class B: 3SM of Visibility, Clear of Clouds.
  • Class G (Below 1,200' AGL): 1SM of Visibility, Clear of Clouds.
  • Class E (Under 10,000' MSL): 3SM of Visibility + 500' Below, 1,000' Above, and 2,000' Horizontally Clear of Clouds.

The weather stations along the majority of your route indicate that current conditions exceed VFR cloud and visibility requirements.

Swayne Martin

Destination Airport Forecast

Hutchinson Airport does not have a TAF, and the closest TAF is over 35 miles away at KRWF. On ForeFlight, there is, however, a "MOS Forecast" for KHCD. The forecast reports that there will be consistent Marginal VFR conditions of 4SM and OVC040 for the next 4 hours. But what exactly is this "MOS?"

ForeFlight

MOS stands for Model Output Statistics. According to ForeFlight, as the name suggests, MOS is derived from the output of weather prediction models developed and run by research meteorologists at NOAA.

Weather prediction models provide forecasters with long and short-term guidance in the form of various meteorologically significant variables like pressure, humidity, temperature, and wind. Meteorologists compile this information and other derived data and display it on standard charts and diagrams to make a forecast.

The job of the MOS is to take these "raw" model forecasts and attempt to improve upon them by issuing site-specific forecasts where a TAF is otherwise not available. MOS takes into account a historical record of observations at forecast points (such as airports), removes any known systematic model biases, and quantifies any uncertainty (like precipitation or thunderstorm chances) into probability forecasts.

Considerations

The snow moving through the area is isolated and light in nature. This isn't a "snow storm" by any means. You're instrument rated and your plane is equipped to fly in instrument conditions, but the trip must be completed under VFR for two reasons:

  • You're not instrument current.
  • You can't fly your Cessna Skyhawk into known icing conditions.
Boldmethod

There's no great way to analyze the conditions below the bands of light snow along your route other than local airport weather reports. Airports to the north and south indicate IFR, but the closest airport to your destination is VFR.

You've always considered yourself a safe, cautious pilot, and you know you have the instrument skills to stay safe if conditions begin to drop. Because you've flown the route before, you're familiar with the terrain and airports nearby. The flight has you stumped because the weather exceeds legal requirements, but you also don't have an adequate way to see where pockets of snowfall will result in conditions becoming IFR.

Is Snow Really "Icing Conditions?"

As winter weather approaches, many pilots are left wondering "is flying through snow icing conditions?" Click here to find out what we learned from the Aviation Weather Center.

There's a lot to take into account here, and there's no "right" answer. The safest option will always be to stay on the ground - there's risk associated with taking off in any airplane.

Should you depart and see how things go, and turn around if conditions underneath the snow showers get worse? We'll leave this one up to you...

What's Your Decision?

Would you go? Why wouldn't you? What would it take for you to make a go/no-go decision? Is there any missing information you need to make the best decision?

Tell us in the comments below, or email us your answer by clicking here.

Swayne Martin

Swayne is an editor at Boldmethod, certified flight instructor, and an Embraer 145 First Officer for a regional airline. He graduated as an aviation major from the University of North Dakota in 2018, holds a PIC Type Rating for Cessna Citation Jets (CE-525), and is a former pilot for Mokulele Airlines. He's the author of articles, quizzes and lists on Boldmethod every week. You can reach Swayne at swayne@boldmethod.com, and follow his flying adventures on his YouTube Channel.

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