Go or No Go: winter warm front

“Messy aviation weather today.” That’s what the forecaster wrote in the forecast discussion this morning and a look at the TV screen in the FBO at the Elkins-Randolph County Airport (EKN) confirms that. The radar images show lots of rain in the area and the forecast is for things to get worse. That’s more than a little annoying, as you’d really like to get back home, a 1:10 flight to Raleigh, North Carolina (RDU).

The good news is that you are very much instrument current, logging 150 hours last year, 50 in the last 3 months and about 35% of your time in actual IFR conditions. Your Cessna Turbo 182 has dual IFR GPSs, an Aspen Primary Flight Display and a good autopilot. It also has a heated pitot tube and a heated prop, but no other deice equipment.

Proposed departure time is 2000Z, about an hour away. Read the weather briefing below, then tell us if you would make the flight.

Overview

The Maps page on ForeFlight has a lot to say today, with rain all over eastern Kentucky, Ohio, and much of West Virginia. Your route of flight does take you away from the worst rain, but there are scattered showers over Virginia.

The surface analysis explains why the radar map is so colorful today – there’s a cold front draped across the Ohio River valley, with low pressure centered in Kentucky.

The prog charts show that front slowly moving into West Virginia overnight, so it’s unlikely tomorrow will be any better. In fact, it will probably be worse.

 

Radar and Satellite

The regional radar shows yellow returns to the west and northeast, but in your immediate area things are more scattered.

The visible satellite shows thick clouds to the north and west, but things appear to thin out as you approach Raleigh.

Icing

Since it’s February, icing is a concern. The good news today is that warm air flowing in from the south has raised the freezing level above 9,000 feet.

Icing is not forecast on the CIP/FIP charts at any altitude below 11,000 feet and there are no PIREPs for icing in your area. There are some AIRMETs for icing, but they are all above your likely cruise altitude.

It looks like 7,000 feet will work today – above the mountains and below the freezing level.

Winds, Turbulence and Storms

There’s definitely rain around, but is it convective? There are no red cells and no lightning, and the convective forecast shows nothing.

Even if there appear to be few storms along your route, there could be turbulence. First you look at the winds aloft forecast.

Then it’s time for a quick glance at the turbulence AIRMETs. The initial picture isn’t too pretty, with low level wind shear forecast over West Virginia:

A closer look at the graphical turbulence forecast looks somewhat colorful to the west but reasonably good for your route of flight.

Text Weather

Now it’s time to review the METARs and TAFs. All that rain must mean IFR conditions, right? Sort of. Your departure airport is surrounded by mountains, but it looks like the bases of the clouds are above the ridges. The forecast doesn’t look good though – as rain moves in, visibility will get worse.

En route, two airports show similar conditions: a relatively high overcast and good visibility.

Your destination is showing good VFR weather and a good forecast. Winds are gusty but mostly down the runway.

Skew-T Diagrams

With a dynamic weather system like this one, some pilots like to review the Skew-t Log-p diagrams to get a 3D sense of the atmosphere. Here is the diagram for Elkins. Winds are pretty steady out of the southwest, and it looks like the cloud tops are above 15,000 feet today.

The diagram for RDU shows those same winds but much thinner clouds:

Decision Time

It’s time to decide whether you’re taking off or canceling. The weather isn’t pretty, but it’s not yet terrible and you are IFR proficient. Do you launch and get home before the front moves through? Or does it look like too much? Add your comment below.

11 Comments

  • Nope — too narrow a squeeze between terrain and the freezing level. As a Canadian pilot, I have a nuanced approach to some types of ice (e.g. rime climbing through a thin SC layer), but I wouldn’t mess around near the SLD from a winter warm front even if I had a piston twin with FIKI. Buy an airline ticket, and come back for your plane next week.

  • David is right about the narrow squeeze.

    ATC may put you at or above the freezing level in visible moisture and some accumulation of rime or mixed ice is a inevitable. If a return to Elkins becomes necessary you’d want to be on the ground by 20:00. The forecast wind could make for a very rough ride over the mountains. Which, incidentally, offer few opportunities for a forced landing.

    On the plus side, the Skylane is an ice-capable airplane and a heated prop is a real asset. Also, the flight would proceed into improving conditions fairly quickly.

    The decision to launch or stay needs to be made quickly or deteriorating conditions will make it for you. David “wouldn’t mess around near the SLD” and neither would I. In addition to the forecast products given here, I’d look at the Forecast Icing Potential charts on the ADDS website. If there was no forecast SLD (supercooled large droplet) icing potential anywhere near the departure or the route of flight, if the airplane was lightly loaded, and, above all, if I was flying alone, I’d probably make the flight.

    • For brevity I left out the FIP charts but they were totally blank for all altitudes below 11,000 and between 11,000 and 13,000 it was a greater than 25% chance of light ice.

  • I think that the flight is safe to make. I am confident enough that there won’t be ice below 9k, but if wrong there seems to be enough equipment to find an out. The out is over the mountains to the south and east which is not ideal, though. The very IFR current and proficent pilot can go I say.

  • Although I’m a firm believer in the saying “ it’s better to be on the ground wishing you were in the air than in the air wishing you were on the ground” this flight looks doable

  • Without any icing pireps, and given that the precipitation is not conventional and pretty IFR proficient I’d launch, but have enough gas to get to a good alternate vs a marginal one.

  • This is a very good “gray area” scenario. I agree pretty much with all the previous comments… I’d decide to “go”… don’t dally much on the ground, depart, keep an eye on OAT, continuously plan an “out” (likely southeast) if not-predicted icing does appear.

  • I would go only if my aircraft had an anti-iced component. The IMC proficiency isn’t, in my opinion, enough when there’s a probability, even a small one, of ice encontrery, in aeroplanes without anti-iced systems.

  • GREAT article, as usual John. I would also add to the weather ‘checklist’ you have provided. Always, ALWAYS take the time to talk with a live weather person at the airport you are leaving from. He or she may have some additional information and/or advice about the weather through out your flight route and destination(s). I did this during the 50 plus years of my flying in the Air Force, Mass. ANG, and our Cessna 182 aircraft ownership/flying… always received some additional information that was VERY useful!

  • I would take a different approach to the trip. I would fly V4 HVQ (Charlestown) V45 PSK Pulaski) RDU. This route keeps me out of the higher terrain longer. When I do cross the terrain is lower, further south so the freezing level should be warmer, and the MEA’s are lower. It looks like 6000 ft works. There are more airports along the route as options if things do not turn out as planned and the crossing over the higher terrain is much quicker since I am crossing perpendicular to the terrain vs flying along it. This route would add about 40 minutes to the flight in my plane but I would be much more comfortable.

    Finally I would redo the weather for this route: metars, TAF’s and skewT’s. Assuming that these verified, I would go.

  • I like your idea to look for an alternate route over the mountains, but with 40 kts and higher winds over the mountains is not my idea of fun. When I flew B-52s on low levels, we were restricted to 39 kts or lower on the winds or no low level flying. At 40 kts we had to abort the route. If I could not do it with a large aircraft, I won’t do it with a small aircraft. If the winds were lower, then I would make the flight. Two summers ago I flew a C172 2000 ft over Mt Washington with a 25 kt headwind and the mountain wave ride I had was very interesting causing my airspeed to very from 65 KIAS to 125 KIAS using full throttle to idle power 3 times. Once I was 15 miles west of the mountain it was smooth descending into Montpelier, VT.

    So with the weather as depicted, no I would not fly.

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